Fluid transfer system and method

ABSTRACT

Devices and methods for automatic monitoring of fluid of a patient are disclosed, comprising a patient line, a transfer disk which receives the fluid and controllably transfers the fluid to test substrates, and a sensor disk which houses the test substrates. The sterile transfer disk may be configured to maintain the sterility of the patient sampling assembly while transferring samples to non-sterile components, such as the sensor disk.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/731,010, filed Mar. 24, 2010, which claims benefit under 35 U.S.C.§119(e) to U.S. Provisional Ser. No. 61/164,285, filed on Mar. 27, 2009,the contents of which are herein incorporated by reference in theirentirety for all purposes.

BACKGROUND

In the health-care industry, diagnostic testing of physiological orbiological samples, such as blood, is a routine, and often cumbersome,task, with physicians requiring a wide variety of specialized tests onpatients' samples to support their diagnoses. With in-patient andcritical care settings, the frequency of blood sampling placesadditional demands on hospital staff.

To satisfy this ever increasing demand for analytical data from samples,sophisticated chemical analyzers have been developed over the past 20years to perform a multiplicity of physical and chemical tests onspecially prepared patients' samples. Sample volume requirements havealso been reduced substantially, to 100 μL or less for some tests.

BRIEF SUMMARY

Devices and methods for automatic monitoring of fluid of a patient aredisclosed, comprising a patient line, a transfer disk which receives thefluid and controllably transfers the fluid to test substrates, and asensor disk which houses the test substrates. The sterile transfer diskmay be configured to maintain the sterility of the patient samplingassembly while transferring samples to non-sterile components, such asthe sensor disk.

One embodiment of a fluid sensor device may comprise at least onetransfer reservoir, wherein each transfer reservoir comprises an inlet,and outlet, and a cavity comprising a displaceable region and alight-reflecting structure. The transfer device may also comprise atleast one alignment structure associated with each transfer reservoir.

Certain variations of a fluid sensor device may also comprise aplurality of transfer reservoirs located in a transfer structure. Othervariations may comprise a plurality of test substrates that are locatedinside a sensor structure, and/or outside the transfer structure. Insome embodiments, the sensor structure is configured to attach to thetransfer structure.

One embodiment of a fluid sensor device may comprise a plurality oftransfer reservoirs, where each reservoir may comprise an opticallytransmissive material, an inlet opening, an outlet opening, and a cavitycomprising a deformable wall and a light-reflecting structure, as wellas a plurality of alignment structures, wherein at least one alignmentstructure is associated with each transfer reservoir.

In some embodiments of a fluid transfer reservoir, the deformable wallsof the plurality of transfer reservoirs are deformable membranes.Optionally, the cavities of the plurality of transfer reservoirs furthercomprise a fixed wall. Certain embodiments of a fluid transfer reservoirare located in a circular transfer housing wherein the inlet openings ofthe plurality of transfer reservoirs are located on the outercircumferential surface of the circular transfer housing. In someembodiments, the transfer housing may be a circular transfer cartridge.

Additionally, the fluid sensor device may further comprise a sensorhousing interface, wherein the interface may comprise an alignmentstructure and at least one locking structure. The sensor housinginterface may further comprise a plurality of sensor substrate accessapertures. In some embodiments, the fluid sensor device may furthercomprise a sensor cartridge comprising a transfer cartridge interfacecomplementary to the sensor cartridge of the transfer cartridge. Certainembodiments of the fluid sensor device also comprise a plurality of testsensors.

Some embodiments of the sensor cartridge further comprise a plurality offluid sample receiving regions, a plurality of sensor substrates and aplurality of sensor electrode contacts. The plurality of fluid samplereceiving regions are oriented to correspond to inlet openings oftransfer reservoirs when the transfer cartridge and sensor cartridge areattached.

Another variation of a fluid monitoring system may comprise a patientaccess interface configured to receive fluid from a patient, a fluidpump configured to transfer fluid in the patient access interface, and avalve coupled to the patient access interface and the fluid pump andcomprising a fluid dispensing opening, wherein the valve is configuredto dispose a fluid sample at the fluid dispensing opening and a fluidinlet blocking structure adjacent to the fluid dispensing opening.

The patient access interface, fluid pump, valve, and fluid inletblocking structure are coupled to a patient line housing. In someembodiments, the fluid monitoring system further comprises an externalfluid access interface configured to receive fluid from an externalfluid source.

Several methods may be employed to monitor the fluid of a patient, forexample, the method may comprise withdrawing fluid from a patient into afirst housing coupled to a fluid monitoring system, transferring a fluidsample from the withdrawn fluid in the first housing to a secondhousing, changing the orientation of the second housing relative to thefirst housing, pumping the fluid sample from the second housing to atest substrate. Pumping the fluid sample from the second housing to thetest substrate may comprise pumping the fluid sample across an air gapbetween a fluid opening of the second housing and the test substrate. Inother variations, pumping the fluid sample from the second housing tothe test substrate may comprise pumping the fluid sample from the secondhousing to a third housing, wherein the test substrate is located in thethird housing. The method may further comprise wiping a dispensingregion of the second housing, and may comprise blocking an opening ofthe second housing the first housing.

Other methods for performing fluid monitoring in a patient may comprisetransferring fluid along a first fluid pathway from a patient to a fluiddispenser, transferring a fluid sample from the fluid dispenser to atransfer reservoir along a second fluid pathway, severing the secondfluid pathway by displacing the transfer reservoir, and activelytransferring at least a portion of the fluid sample from the transferreservoir to a test substrate along a third fluid pathway. The methodmay further comprise crossing an air gap between the transfer reservoirand the test substrate with the fluid sample. In some variations, atleast portion of the cross-sectional shape of the fluid sample isunrestrained in a transverse plane along a movement axis of the thirdfluid pathway.

An alternate method for performing blood monitoring of a patient maycomprise withdrawing blood from a patient into a fluid control system,dispensing a blood sample from the sterile fluid control system to asterile transfer reservoir, and transferring the blood sample from thesterile transfer reservoir to a non-sterile test substrate. The methodmay comprise moving the sterile transfer reservoir with respect to thefluid control system after dispensing the blood sample, wherein movingthe sterile reservoir occurs before transferring the blood sample.Transferring the blood sample may comprise pumping the blood sample fromthe sterile transfer reservoir to a non-sterile test substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a fluid monitoring system used to monitor blood glucoselevels in a patient.

FIGS. 2A-2C depict one embodiment of the housing of a patient line (PL)cartridge.

FIGS. 2D-2F depict the arrangement of fluidic devices in the PLcartridge of FIGS. 2A-2C.

FIGS. 2G-H depict one embodiment of a pressure sensor used in the PLcartridge.

FIGS. 2I-2M depict one embodiment of a multiplexing valve used in the PLcartridge.

FIG. 2M-1 illustrates one variation of the dispense nozzle shape.

FIGS. 2N-2O depict a sequence of fluidic connections that may be used bythe fluid monitoring system during initialization, sample collection,and sample dispensing.

FIG. 3 depicts one embodiment of a multi-component disk assembly.

FIGS. 4A-4B depict one embodiment of the transfer disk that may be usedin a multi-component disk assembly.

FIGS. 4C-4E depict one embodiment of the transfer disk structure.

FIGS. 4F-4G depict a pump mechanism that may be used to urge a fluidsample in a transfer reservoir.

FIGS. 4H-4L depict various aspects and components of the transfer diskstructure, including the transfer reservoir, inlets and outlets, and thetotal internal reflection minors and light path for optical sensing of afluid sample (e.g. blood).

FIGS. 5A-5B depict the components of one embodiment of a sensor disk.

FIGS. 5C-5E depict one embodiment of the sensor disk structure.

FIGS. 5F-5J depict various aspects of the sensor disk and sensorinterface.

FIG. 5K depicts an example of a shelf-life vs. humidity curve.

FIG. 5L depicts an integration routine that may be used to estimate theshelf-life of test sensors under changing humidity conditions.

FIGS. 6A-6D depict various aspects of the interface between a transferdisk and sensor disk.

FIG. 7 depicts a possible load configuration of the PL cartridge anddisk assembly.

FIGS. 8A-D depict different functional configurations (such as dispense,withdraw, index, and wipe) of the PL cartridge and disk assembly.

FIGS. 9A-9C depict the various mechanisms that regulate fluid flow fromthe PL cartridge to the transfer disk to the sensor disk.

FIGS. 10A-10C depict an example of sterile packaging for a disk assemblycomponent.

FIGS. 11A-11B depict a variation of the system interface for the patientline and housing and disk assembly.

DETAILED DESCRIPTION

FIG. 1 schematically depicts one embodiment of an automated fluidmonitoring system. In this particular embodiment, the fluid monitoringsystem is a blood monitoring system (165), but in other embodiments, afluid monitoring system may be used with other body fluids or organsystems. The blood monitoring system (165) may be organized into severalcomponents: a patient line (PL) and housing assembly (195), a monitorassembly (167), a transfer and sensor element such as disk assembly(188), and a flush and KVO (“keep vein open” or “keep vessel open”)fluid system (169). The patient line and housing assembly (195), whichmay also be called the patient access line (PAL) and housing assembly,comprises a fluid access device (171) attachable to the patient (50) anda series of fluid channels or pathways connecting the fluid accessdevice (171) to a fluid sample dispenser or dispense valve (173), a pump(198), fluid system and other components. The fluid access device (171)may be configured to access any of a variety of sites, including but notlimited to peripheral and central vascular access sites, arterial andvenous vascular sites, lymphatic sites, urinary tract sites, cerebralspinal fluid sites in the spine and cranium, intraabdominal andintrapleural fluid sites, etc.

A transfer element is a portion of the system that is configured totransfer (either directly or indirectly through an intermediary) asample from a patient line to a sensor element. A sensor element is aportion of the system that is configured to sense at least one parameterof a transferred sample. One embodiment of a transfer and sensor elementis disk assembly (188) in FIG. 1, comprising a transfer disk (196) and asensor disk (190) which includes a plurality of test sensors (161) withtest substrates (199). The transfer disk (196) may be locked intoengagement with sensor disk (190) when in use. Once locked together, thetransfer disk (196) and sensor disk (190) may not be separated so thatthey cannot be reused and are generally disposed of together after use.In other embodiments, the transfer and sensor element may be an assemblyof cassettes, cartridges, or may be enclosed in a single housing. Thetransfer element or transfer disk, or sensor element or sensor disk maycomprise a variety of shapes and/or configurations of test sensors ortest substrates not limited to a disk shape.

The transfer disk (196) in FIG. 1 provides a plurality of fluid samplecavities or conduits (189) that separate and transport a fluid sample(175) from the fluid sample dispenser (173) to a test sensor substrate(199) of the sensor disk (190). The transfer disk (196) furthercomprises a plurality of transfer pumps (197) each corresponding to aconduit or cavity (189) and configured to pump a sample from the conduitor cavity to a corresponding test substrate. According to someembodiments, the transfer pumps comprise deformable members whichcommunicate with the conduit or cavity (189). An enclosed cavitycontaining a sample opens towards a test substrate (199). Upondeformation of the transfer pump (197), the sample is pumped, displaced,transported or pushed towards a test substrate (199). A pump actuator(197 a) may be separately controlled. In some embodiments, e.g., asillustrated, the pump actuator is located on the monitor (167) and maybe mechanical or electrical in nature. It communicates via interface 1with the control system (185).

By using a transfer disk (196) instead of directly dispensing a fluidsample (175) to the test substrate (199), the risk of contaminationspreading or bridging back from the non sterile sensor disk (190) to thesterile (or non-contaminated) patient line and housing assembly (195) orthe patient (50) may be reduced. Also, by providing sterile, single-useintermediate structures between the fluid sample dispenser (173) and thetest substrates (199), the test substrates (199) do not requiresterilization themselves, which may improve the shelf-life, operatingrange, and/or operating performance of the chemicals or reagents, ifany, comprising the test substrates (199).

After transferring a fluid sample (175) to the sensor disk (190), thefluid sample (175) may react with the chemicals, reagents, or othercomponents of a test substrate (199) and the resulting end product isproduced in proportion to the analyte level in the fluid sample, whichcan then be analyzed by the monitor assembly (167) to determine theanalyte level or other fluid parameter measurements. In the particularembodiment depicted in FIG. 1, the blood monitoring system (165) isconfigured to measure blood glucose using a blood glucose monitor(“BGM”) assembly of the monitor assembly (167), but in otherembodiments, other analyte or parameter measurement components may beprovided in addition or in lieu of the BGM.

As mentioned previously, the transfer disk and/or sensor disk maycomprise any of a variety of designs, including but not limited todrums, carousels, clips, cassettes, or any other module configured tointerface or insert into another component. In some embodiments, thepatient line and housing assembly (195), the flush and KVO fluid system(169), and/or the monitor assembly (167) may also be in a cartridge orother swappable or modular form factor. In some embodiments, two or morecomponents may be integrated into a single chassis or structure. In someembodiments, for example, the transfer disk (196) and the sensor disk(190) may be integrated into a single cartridge (disk assembly (188)),while in other embodiments, the patient line and housing assembly (195)may be integrated with one or more components of the flush and KVO fluidsystem (169).

As depicted schematically in FIG. 1, the patient line and housingassembly (195) comprises a main access line (177) from which fluid maybe withdrawn and/or infused with respect to the patient (50). The mainaccess line may include a luer lock (177 a) that may be connectable to avariety of types of fluid access devices (171) or catheters such asperipherally inserted venous catheters, peripherally inserted centralcatheters, central venous catheters, or arterial lines. Accordingly thesystem may be adaptable to connect to a catheter or other blood accessdevice already positioned in the patient. In this particular embodiment,the main access line (177) includes an air in line detector (178). Theair in line detector (178) may be useful for safety purposes to makesure that during any infusion or reinfusion procedures through the mainaccess line (177), limited air is being infused. The patient line andhousing assembly (195) may include a bubble removal port which can beused to manually remove air bubbles or take fluid samples from thepatient line fluid circuit. The air in line detector (178) may be anoptical, acoustic, chemical, or impedance-based detector, but any otherdetector design may also be used.

The fluid dispenser (173) is used to dispense a fluid sample or fluiddroplet to the transfer disk. In the particular embodiment depicted inFIG. 1, the fluid sample dispenser (173) is a dispense valve, but inother embodiments, the fluid sample dispenser (173) may comprise amembrane or a spray nozzle, for example. The fluid sample dispenser(173) may be combined into one unit with a fluid selector valve (181) asrepresented by bracket (111) in FIG. 1. Fluid dispense valve (173) andfluid selector valve (181) may be combined in a way that permits certainconnection configurations while prohibiting others. For example, theconfiguration of the dispense-selector combination valve that allows thevolume reservoir (183) to be connected to the dispense valve nozzlewould simultaneously prevent any fluid connections between the syringeand the KVO flush solution. The dispense-selector combination valve maybe arranged in any way to permit or prohibit fluid connections asrequired by the operation of the fluid monitoring system.

The fluid sample dispenser (173) is connected to an optional blooddetector (180). The blood detector (180) may be used by the monitorassembly (167) to determine whether blood has been adequately withdrawnfrom the patient (50). For example, the monitor assembly (167) may useblood detection as a pre-condition for dispensing a fluid sample fromthe fluid sample dispenser (173). This may be necessary to ensure thatnon-diluted blood has reached the fluid sample dispenser (173) becausethe patient line may be filled with flush solution prior to withdrawinga patient sample. Also, in some instances, flow resistance and/orclotting may reduce the blood flow in the blood monitoring system (165).By providing a blood detector (180), the action of the pump (198) may beadjusted to compensate for changes in fluid flow and/or to provide awarning signal. In some instances, the monitor assembly (167) may beconfigured to cease operation or initiate an unclogging or othercorrective procedure when certain operating states are identified by theblood detector (180) or air in line detector (178), for example. This isdescribed in U.S. application Ser. No. 11/386,078, which is herebyincorporated by reference in its entirety. The blood detector may be anoptical blood detector, a chemical-based, acoustic-based,impedance-based, or other type of detector. The fluid sample dispenser(173) also comprises an actuator or motor for controlling theconfiguration or state (e.g. open or closed) of the dispenser (173), andmay also include one or more sensors that may be used to detectdispenser malfunction or to provide feedback to control valve function.

The blood detector (180) is connected to a fluid selector valve (181)which is in fluid communication with a pressure sensor (182). The fluidselector valve (181) is configured to selectively provide communicationbetween two or more of its ports. In this embodiment, the pressuresensor (182) is shown positioned between the syringe (198) and the valve(181). Various embodiments of the fluid selector valve are described ingreater detail below. In the particular embodiment depicted in FIG. 1,the fluid selector valve (181) in combination with the dispense valve(as indicated by bracket (111)) comprises at least five ports. However,in other embodiments, a greater or less number of ports and/or valvesmay be provided and/or used. A pressure sensor (182) is positioned inthe tubing that runs between the syringe (198), selector valve (181) andvolume reservoir (183), but in other embodiments, one or more pressuresensors may be connected in other locations in proximity to the fluidselector valve (181), may be integrated with the syringe pump, or may bepositioned in-line along other portions of the blood monitoring system(165) including but not limited to at the catheter or fluid access site(171). As depicted, the ports of the fluid selector valve (181) areconnected to a pump (198) and a flush and KVO solution (169). Anoptional fluid reservoir (183) is also provided between the pressuresensor (182) and the blood detector (180). In some instances, the fluidreservoir (183) may be used to ensure that a sufficient volume withinthe patient line fluid circuit exists to ensure that samples from thepatient are not able to contact the pump (198), pressure sensor (182) orfluid selector valve (181). In other instances, the fluid reservoir(183) may act as a sump which may reduce the precision needed for one ormore processes. In some embodiments, an additional port may be providedfor a waste disposal line or component. The waste disposal line may beused, for example, for expelling clots or bubbles in the bloodmonitoring system (165), and/or for clearing certain types of fluids outof the fluid lines. The waste disposal may take blood saline mixture outthat is created when blood is drawn. This may be used in particularlyfluid sensitive patients or to avoid infusing excess solution back intoa patient. In one specific example, the blood monitoring system (165)may include a cleansing solution that is periodically infused into thesystem to resist biofilm buildup and/or clot formation but is preferablynot infused into the patient. The waste disposal line may be used toexpel the cleansing solution from the system, along with additionalflush solution, from the fluid channels before restarting any KVOinfusion or fluid sampling. In other embodiments, a separate wastedisposal line and/or valve may be provided elsewhere along the system.

The fluid selector valve (181) and/or the fluid sample dispenser (173)may be manipulated by the monitor assembly (167) using any of a varietyof actuating mechanisms. These mechanisms include but are not limited toa stepper motor, servo motor or electromagnetic motor. The motor may beelectric, hydraulic, pneumatic or magnetic-based, or electro-magnetic,for example.

The pump (198) connected to the fluid selector valve (181) may be any ofa variety of pumps, including but not limited to a syringe pumps, pistonpumps, diaphragm pumps, peristaltic pumps, and the like. The pump (198)may be bidirectional or multidirectional. The pump (198) may bedisposable. The pump (198) may comprise an opening with which fluid maybe withdrawn and infused. In other embodiments, however, separate inletand openings may be provided.

In the particular embodiment illustrated in FIG. 1, a single solutionsource is provided, comprising a flush and KVO solution (169) to be usedwith the flush and KVO solution set (169). The solution source may beconnected to the blood monitoring system (165) using a spike dripchamber (184) which is used with standard intravenous fluid bags, but inother embodiments, any of a variety of other fluid connectors may beused and multiple fluid sources for multiple fluids or solutions may beused. The solutions that may be used with the blood monitoring system(165) include but are not limited to distilled water, normal saline,half-normal saline, D5W, and Lactated Ringer's solution. In someembodiments, the solution may contain one or more additives, includingbut not limited to heparin, a heparinoid, potassium, magnesium, sodiumbicarbonate, multi-vitamin solution, anti-infectives such as antibioticsand anti-fungal agents, for example, provided the solution does notsignificantly interfere with the analyte to be measured or provided thesolution can be adequately be compensated for when the analyte ismeasured.

The flush and KVO solution set (169) may be used to infuse intravenousfluids into the patient (50) in between blood sampling procedures. Itmay also be used to open an occlusion or venous valve to improve blooddraw. As noted previously, the flush and KVO solution bag or source maybe accessed using a spike drip chamber (184) or other type of accessdevice. Although characterized as a “Keep-Vein-Open” solution set,higher infusion rates may be provided also. For example, typical KVO (orTKO “To-Keep-Open”) infusion rates are about 50 mL/hour or less, butinfusion rates greater than 50 mL/hour may be provided. The higher ratesmay be about 75 mL/hour, about 100 mL/hour, about 125 mL/hour, about 150mL/hour, or more. The infusion rate may be an average rate or may bedelivered as a bolus or a plurality of boli over a period of time.

The monitor assembly (167) comprises a control system (185) orprogrammable logic controller that is configured to receive and processsensor information and to control and coordinate a variety of processesperformed by the blood monitoring system (165). The control system (185)receives data from a blood glucose monitor (“BGM”) (186) through a BGMinterface (16) which receives data from read head (187) via interface(12). The BGM interface (16) and other interfaces of the system (165)may be unidirectional (e.g. input or output only, such as receiving datafrom the BGM) or bi-directional (e.g. receiving data and transmittingcontrol signals to initiate a warm-up procedure or enter calibration ormaintenance mode, or to transmit other data, such as control system,environmental, patient, or situational data, necessary for the user orpractitioner). The BGM (186) may be configured to directly or indirectlyanalyze the test substrate (199). In the embodiment depicted in FIG. 1,a read head (187) which is part of the monitor (167) is positionablewith respect to disk assembly (188), to read the test substrate (199)and to communicate the control system (185). According to someembodiments, an access opening is provided for positioning the read head(187) adjacent the test substrate (199). The interface (13) may be aconnector or a set of electrical contacts which allows the read head toread from test substrate (199) when coupled thereto. The interface (11)allows the control system (185) to control operation of the read head(187). The BGM (186) may alternatively communicate with any other systemwhich would provide an intermediate structure between the dispense valve(173) and the test substrates (199) or that would allow reading of thetest substrate (199) and communication with the control system (185).According to some embodiments, a humidity sensor (167 j) is mounted inthe monitor (167) adjacent to the sensor disk (190). The humidity sensorcommunicates to control system (185) via interface (27) which then mayadjust the blood glucose reading based on sensing humidity or humidityover time and corresponding sensor sensitivity level. The humiditysensor (167 j) may also provide humidity sensor reading or readings thatindicate that a sensor is no longer sufficiently sensitive or accuratethus signaling replacement of the disk assembly (188) is required.According to some embodiments, the sensor life and/or accuracy and/orprecision is determined at different humidity levels. A curve is createdof the life or accuracy or precision of the sensor based on humidity.Humidity at the sensor is monitored before and during use. The humidityis integrated over time where the integration is weighted depending onthe sensitivity at the different humidity levels. When the integratedhumidity reaches a level determined to be the limit where the sensor nolonger produces acceptable results, the monitor indicates replacement isnecessary. Alternatively, the monitor may adjust the output reading tocompensate for the humidity effects.

A disk assembly drive (191) is provided having an actuating mechanism(e.g. a motor with a rotor) that provides movement and positioning ofthe disk assembly (188) with respect to the monitor (167) (includingpositioning of read head (187) and transfer pump actuator (197 a), withrespect to a transfer pump (197) of a transfer conduit or cavity (189)of the disk assembly (188)). The disk assembly drive (191) advances,rotates, pivots or otherwise manipulates the disk assembly (188) toselect the desired conduit or cavity (189) of the transfer disk (196)and corresponding test substrate (199) of the sensor disk (190), intoand out of a dispensing position with respect to the fluid sampledispenser (173). The disk assembly drive (191) provides for control andselection of disk assembly (188) positions for purposes including butnot limited to dispensing to transfer conduit or cavity (189), wiping orblotting the dispenser (173) with a wipe positioned on the disk assembly(188), separating individual components from each other or contactingindividual components with each other, or initiating a test sensorreading as well as checking test sensor use status. In some embodiments,the interface (14) may also allow the disk assembly drive (191) totransmit signals to the control system (185) indicative of variousoperating parameters, for example position of the disk assembly (188).The disk assembly drive may be composed of a single acting mechanismdriven directly or indirectly by but not limited to a stepper motor,servo motor, or DC motor. Alternatively the drive assembly may becomprised of two or more assemblies, such as but not limited to a cam toprovide pivoting action and a spindle to provide rotary motion. Suchmechanism may be actuated by solenoids, DC motors, servo motors, orstepper motors.

In the embodiment depicted in FIG. 1, the monitor assembly (167) furthercomprises a electrical interface (4) between the control system (185)and the pump (198). The configuration of the software may vary,depending upon the desired functionality. For example, the software maybe configured to control the pump (198) based upon plunger motion rate,plunger force, plunger home position, plunger end position or anyposition therebetween. The electrical interface may comprise any type ofstandardized interface, or a proprietary interface. For some components,an analog/digital converter may be provided in the component itself, thesignal interface and/or the control system (185). In embodimentscomprising an optional infusion pump for one or more fluid sourcesconnected to the blood monitoring system (165), an infusion pumpinterface may also be provided.

The monitor assembly (167) may also comprise a distribution valveinterface (3) (or interface with multifunction valve, a combination ofdistribution valve (181) and dispense valve (173)), which transmitscontrol signals to the mechanical drive of the multi-port distributionvalve or fluid selector valve (181), and optionally transmits valveposition information back to the control system (185). A unidirectionalor bidirectional interface may also be provided for the fluid sampledispenser (173) to transmit control signals and dispenser positioninformation.

In embodiments comprising a stand-alone inline pressure sensor or apressure sensor integrated with the multi-port distribution valve orfluid selector valve (181), a pressure sensor interface (2) is providedto transmit pressure sensor information to the control system (185).Other data input interfaces that may be provided include but are notlimited to the air detector interface (6) and the blood detectorinterface (8).

In some embodiments, the monitor assembly (167) is configured withsensors to detect the coupling and/or proper seating of one or morecomponents of the blood monitoring system (165). For example, a patientline in place sensor (193) may be provided to detect whether the patientline and housing assembly (195) is in place. The control system (185)may use the sensor (193) to check the status of the patient line andhousing assembly (195) before proceeding with its operation, or withcertain maintenance or corrective procedures. In some embodiments, areleasable PL lock between the patient line and housing assembly (195)and the monitor assembly (167) may be provided. The releasable PL lockmay form a mechanical interlock with the PL and housing assembly (167)which is electronically releasable to prevent removal of the patientline and housing assembly (195) during operation or during certainprocedures, and which may protect the clinician, patient (50), and/orthe blood monitoring system (165) from damage. The transfer disk (196)may also be provided with a transfer disk in place sensor (179) whichcommunicates with the control system (185) through signal interface(15). The sensor disk (190) may also be provided with a sensor disk inplace sensor (192) which communicates with the control system (185)through signal interface (7). An optional sensor or communicationinterface may be provided between the PL and housing assembly (195) andthe disk assembly to confirm alignment between the two components.Specific examples of the interface between the disk assembly (188), thepatient line and housing (195), and other components are described belowand also described in U.S. application Ser. No. 12/057,245, which ishereby incorporated by reference in its entirety.

In addition to detecting and identifying the placement of modules in theblood monitoring system (165), a fill sensor (192 a) provided to detectwhen a cavity or conduit (189) has reached maximum fill level. Conduit(189) may also be a cavity, conduit, tube, well, sample reservoir, orother structure that may be used to retain or contain a fluid sample.This prevents over and under fill of the transfer conduit so that it isassured that the fluid sample from the patient does not over fill theconduit and bridge to a non-sterile component before the dispense valve(173) is withdrawn from contact with the transfer disk (196). Inaddition, the fill sensor may provide feedback that the well has beenfilled adequately by the pump so as to ensure successful transfer offluid from the transfer disk to the test substrate or test sensor. Inaddition, the pressure sensor may be used prior to dispensing todetermine if the fluid is at a pressure is stable and/or close toambient pressure or offset from ambient pressure by a given amount thusproviding a more controlled or reliable dispense of fluid.

A variety of sensors may be used including, e.g. an opticallytransmissive, optically reflective, electrically conductive orcapacitive sensor. The sensors may be separate elements, a plurality ofelements, and/or may be integral with the disk. The test sensor may besingle use. It may be pre-calibrated, e.g. to permit ease of use. Acontrol solution, e.g., of a known analyte concentration, may bepositioned in one of the test sensor locations and may be used todetermine at time of used of sensor element the efficacy of the sensors.For example, if the sensitivity of a sensor has changed duringtransportation, or over time, the sensor reading may be compared withsensitivity that is input into the RFID tag at time of manufacture,packaging or transport. The sensor readings may be corrected accordinglyor an indication may be provided if the sensor disk should be replaced.The fill sensor (192 a) may communicate via interface (15) with controlsystem (185). The fill sensor (192 a) communicates with the controlsystem via interface (5).

In addition to detecting and identifying the placement of modules in theblood monitoring system (165), door sensors (167 f) may also be providedto detect when one or more access doors of the system (165) have beenopened. In some embodiments, detection of open access doors may stop orlimit operation to protect against danger to the patient, the clinician,or to the equipment or warn the user to close the door to maintain theintegrity of the chamber within the monitoring system (165).

In some embodiments, one or more components or modules of the bloodmonitoring system (165) may comprise machine readable indicia that maybe relayed to the control system (185) using an indicia reader and maybe used to provide information concerning the particular component ormodule. The indicia reader may be, for example, a barcode reader, aradiofrequency ID (RFID) chip reader (194 a), and/or an electricalconnection to an EPROM or other chip located on one of the consumablecomponents (e.g., the transfer disk, sensor disk or patient line). Themachine readable indicia may comprise graphical indicia such as abarcode, or intangible indicia such as an RFID chip (194). In someembodiments, the information may comprise serial numbers or arbitraryidentification information that may be compared to a database within thecontrol system (185) to confirm that the correct type of cartridge wasinserted, and/or to configure the blood monitoring system (165). Inother embodiments, the machine readable indicia may includeconfiguration information, such as calibration curves or thresholdvalues that may be used to configure the control system (185) and/or BGM(186) without utilizing a look-up database. With the latter embodiments,the software of the control system (185) does not require updating inorder to utilize a new type of test substrate cartridge, because theconfiguration and/or calibration information may be provided through themachine readable indicia. In some embodiments, the monitoring system(165) may be configured so that the machine readable indicia of acartridge or module may be read by the control system (185) before thecartridge is fully seated and locked into place. If the control system(185) identifies the particular cartridge or module as an incorrectmodule (e.g. wrong patient, incompatible with the particular PL andhousing assembly (195) or with the selected monitoring function), insome embodiments, the control system (185) may control the module locksto block their seating or insertion into the monitoring system (165), orby rejecting via a screen alarm is detected after seating in place. Insome embodiments, the control system (185) may comprise a separateindicia writer, or a writing function may be integrated into the indiciareader. The writing function may permit, for example, an RFID chip to beprogrammed to flag the cartridge as having been used, with or withoutpatient information or for patient-specific, operational use, or errorinformation to be written to the RFID chip for later analysis,documentation, or troubleshooting by the user or manufacturer. Thewriting function may also prevent inadvertent use of an incorrectcartridge or module. In other embodiments, the writing function may beprovided by barcode printer which prints and applies printing, e.g.inkjetting, a new barcode on the cartridge or module.

In addition to the interfacing with other components of the bloodmonitoring system (165), the monitor assembly (167) may further compriseone or more subcomponents for interfacing with medical staff, medicalinformation systems or other extrinsic systems. In the embodimentdepicted in FIG. 1, these subcomponents may include a graphics displayof text (167 a) and/or pictorial information (e.g. graphical plots) ofpatient related information and/or system status information, othertypes of indicator lights (167 c) (e.g. LEDs), operator input devices(167 b) (e.g. keyboard, touch screen, joystick, mouse, buttons, dials,bar code reader), a hospital information system port (167 d) (e.g. fortransmitting information to a remote patient monitor at a nursingstation and/or for storing results in an electronic medical record), oneor more external patient sensors (194 b) communicating with an externalsensor interface (167 k) (e.g. wirelessly or through a connection orother intermediate communication device), a diagnostic port to performmaintenance updates or diagnostic checks of the system or software,environmental sensors (167 h) (e.g. temperature, barometric pressuredetectors), auditory/visual/tactile alarms forpatient/environmental/system-related warnings/fault states (167 e), andpower/battery status monitors or sensors (167 g). Data interfaces (9,10, 17, 18, 19, 20, 21, 22, 23, 24, 25 and 26) may be provided for therespective components. The data interfaces for these components may beunidirectional or bidirectional. The data interface (26) for thehospital information system port, for example, may transmit patientand/or system data out of the port, but may also receive data from theexternal information system (e.g. signal to change system function, orto alter the type or presentation of patient and/or system data). Theexternal patient sensor may include a sensor apparatus that isconfigured to sense or determine one or more parameter corresponding toa patient or patient treatment, such as, e.g., patient temperature orlimb temperature, heart rate, pulse, EKG, blood pressure, respirationrate, blood gas level (e.g., oxygen or carbon dioxide, e.g., via pulseoximetry or an indwelling catheter), Hematocrit, blood viscosity, drugtype, drug dosing or infusion rates, or other parameters. The sensedpatient parameter and/or environmental, room temperature, humidityinformation may be used to adjust patient draw parameters, adjustglucose or other measurements made at sensor disk or to improve accuracyor precision of readings by the blood glucose or other analyte monitor.

In some embodiments, one or more of the subcomponents may provideinstructions or instructional indicia to a person, for example, toperform a check or other procedure (e.g. check for a clog or air in thefluid line, replace empty IV bag or test sensor cartridge). In someembodiments of the blood monitoring system where the manipulation offluid samples or fluid droplets is gravity dependent, the monitorassembly (167) may comprise a tilt detector (167 i) which may provide awarning when the system (165) is not adequately level, or may evenprovide specific auditory and/or visual instructions to adjust specificfeet, or supports of the system, up or down to achieve the desiredleveling. In other embodiments, the control system may comprise motorsor other mechanisms to automate procedures such as leveling, cartridgechange or IV bag change, for example.

Patient Line and Housing

As mentioned previously, certain components of the fluid monitoringsystem may be provided in removable housings and/or cartridges, whichmay facilitate replacement of disposable components and/or sterilizationof reusable components. A cartridge may refer to any unit, cassette,drum, or assembly of parts, which may be enclosed in a housing. Somevariations of the patient line and housing (195) in FIG. 1 may comprisea number of system components found between the patient and the sensorsubstrate. One specific embodiment of a PL and housing (200) is shown inFIGS. 2A and 2B. The housing (201) is made of a co-polyester blend, butmay be made of any material with similar properties, such aspolycarbonate or acrylic. PL cartridge (200) may comprise one or moreconnectors that transfer fluid in and/or out of the cartridge. Here,fluid connectors (202) and (204) are provided to connect PL cartridge(200) to components of the fluid monitoring system, such as the KVO andflush solution reservoir (169), or the fluid access device (171), whichis attached to the patient (50). In other embodiments, additionalconnectors may be provided for additional fluid lines, separate flushsolutions, optional waste circuits, and/or intravascular hemodynamicmonitoring sensors, for example. A dispensing valve (206) transfersfluid samples obtained from the patient (50) to the other components ofsystem, such as the transfer cartridge or sensor cartridge that aredescribed in greater detail below. The PL cartridge (200) may alsocomprise other structures which may facilitate or coordinate fluidtransfer to the other components or between other components, such asthe fluid channel plug (224), which is described in greater detailbelow.

PL cartridge (200) may comprise several alignment features. Thesealignment features may be used to ensure correction positioning andalignment with respect to other system components. For example,alignment protrusions (207 b) and (207 d) may be used to mechanicallyalign the PL cartridge to the monitor during installation and use. Insome embodiments, mechanical interlock features may be temporary, sothat the PL cartridge may be removed and/or disposed after use.Apertures may also be provided for alignment, which are described indetail below.

PL cartridge (200) may comprise mechanical and electrical interfacesthat allow the fluid monitoring system to control and acquire data fromcertain components within the PL cartridge (200) and acquire data fromthe cartridge (200). There may be various apertures in the housing(201), for example, aperture (203) which may facilitate the handling ofthe PL cartridge (200). Aperture (205) may be sized and shaped to permitthe insertion and actuation of a pump, for example, a syringe pump.Additional apertures may be included to allow actuators to manipulatethe components of PL cartridge (200) for example, as described in somevariations herein. In some variations, there may be apertures that allowmechanical sub components within the PL cartridge to manipulate externalstructures. Some variations of the PL cartridge may comprise aperturesin the back of the housing (201), as shown in FIG. 2C. These apertures(227, 218, 220, 229) may provide access to the internal components ofthe PL cartridge, as well as engage with alignment protrusions. Forexample, apertures (227, 218, 220, 229) may allow sensors (e.g. opticalsensors) to access the contents of the fluid channels in the housing(201). In some variations, access apertures (227, 218, 220, 229) may belocated in the front of the housing (201). Apertures (207 b) and (207 d)may form a mechanical interface with protrusions on the fluid monitoringsystem, to align and secure the PL cartridge within the system. Accessapertures (227, 218, 220, 229) may also be used to aid in debugging thePL cartridge (200) if a malfunction occurs. Assembly apertures, forexample, holes (207 a) and (209 b), may be provided as junction pointsto secure multiple components together. Holes (207 a) and (209 b) may besized and shaped to accommodate screws and connectors to secure thecomponents of PL cartridge (200).

The PL cartridge (200) may also comprise an electrical interface thatprovides power to the components in the cartridge. This electricalinterface may also allow commands to be issued from the control system(185) to the PL cartridge, and for data readings (e.g. from varioussensors) to be transmitted back to the control system. For example,control system (185) may probe an internal sensor (e.g. a pressuresensor) using an electrical interface (219), as shown in FIG. 2C.Different sensors may use a variety of interfaces, e.g., any standard orproprietary interface, electrical or otherwise, to communicate betweenthe PL cartridge and the control system, as shown in FIG. 1.

The connectors, apertures, and electrical interfaces described above maybe covered prior to their installation and use within the fluidmonitoring system. For example, cover (208) may be locked onto the PLcartridge prior to installation by attaching to retention features (223a) and (223 b), and may only be unlocked when properly installed in thefluid monitoring system. Covers may also be temporarily attached to thehousing (201) by adhesives, hook-and-loop fasteners, static cling, orany suitable bonding method. The covers may be rigid or flexible,depending on its material composition. Covers (e.g. cover (208)) mayoptionally be used to align the PL cartridge during assembly andinstallation. Some variations of the PL cartridge (200) may include suchcovers to reduce contaminants from entering the apertures, protectconnectors and other protruding features from damage, and to guardagainst device tampering. Other fluid monitoring system components, suchas the disposable elements, may also comprise such covers.

Referring to FIGS. 2C and 2D, the fluid flow between the patient and thesensor substrate may be managed using any number of tubes, valves,connectors, and pumps arranged in any suitable configuration. In PLcartridge (200), the fluid-regulating system comprises a pump (210),tubing (214), a pressure sensor (216), fluid reservoir (222), and fluiddispensing or multiplexing valve (206). These fluidic devices may beplaced in any suitable position in the PL cartridge, an example of whichis shown in FIG. 2D. These devices may also be interconnected by atubing assembly (214) in any suitable configuration, as shown in FIG.2E. In certain variations, connector (202) and the tubing running fromit may connect the KVO and/or flush solution (169) to the multiplexingvalve (206). Connector (204) and the associated tubing may connector thepatient device (171) to the multiplexing valve (206). The tubingassembly (214) may also provide connectivity between the pump (210) andthe fluid reservoir (222) and multiplexing valve (206). Tubing assembly(214) may also provide connectivity between the fluid reservoir (222)and the multiplexing valve (206). While the tubing assembly (214)provides general connectivity between these fluidic devices, the fluidconnections may change during the use of the monitoring system and ismanaged by the control system (185). The control system may actuate themultiplexing valve (206) to select for certain fluid connections, andmay also actuate the pump (210) to encourage fluid flow to or from theconnected components.

Syringe Pump

The fluid flow through the PL cartridge (200) may be controlled by avariety of pumps, for example, infusion pumps, centrifugal pumps, pistonpumps, diaphragm pumps, syringe pumps, peristaltic pumps, and the like.In one variation of a PL cartridge, a syringe pump (210) is used toregulate fluid flow, as shown in FIG. 2D. The plunger (211) of thesyringe pump may extend out of the housing through aperture (205) andmay be actuated by either an external or internal component, such as alever or motor, which is controlled by the control system (185). Thesize of the syringe (210) may vary as needed. For example, a syringepump in a blood monitoring system that monitors one blood analyte mayneed to regulate 5-10 mL of blood. A syringe pump in a blood monitoringsystem that monitors multiple blood analytes or process several fluidsmay need to regulate more than 10 mL of blood. The pressure gradientcreated by the syringe (210) may be used to move fluid into, out of, andwithin the tubing assembly (214). For example, the pressure gradientcreated by the syringe pump (210) may be used to draw fluid from (orpump fluid to) an external fluid source, such as the patient (50) or theKVO solution (169). The syringe pump (210) may also be used to movefluid from the fluid reservoir (222) to the multiplexing valve (206). Incertain variations, the syringe pump may be sterilized prior toinstallation and use, and made of materials that can withstand thesterilization procedure, such that reliability is not compromised. Theinterface between the pump and the fluid tubing may vary depending onthe pump type. For example, a luer lock (212) may act as the junctionbetween syringe pump (210) and PL cartridge tubing assembly (214),however any locking interface that is fluid-tight (either through alocking mechanism or by bonding) may be used. In the variation of the PLcartridge shown in FIGS. 2D and 2E, the body of the syringe pump (210)is enclosed by the fluid reservoir (222), however, the pump (210) may bepositioned elsewhere, and not necessarily enclosed by the fluidreservoir (222).

Fluid Reservoir

Certain variations may have a fluid reservoir (222). In some instances,the fluid reservoir (222) is used to ensure that sufficient volumewithin the PL fluid circuit exists to ensure that samples from thepatient are not able to contact the pump (210), pressure sensor (216),or other components. Alternatively, fluid reservoir (222) may act as asump and reduce the precision needed for one or more processes. Thefluid reservoir may be of any suitable configuration such that an excessof fluid may be stored therein and readily drawn for testing. In somevariations, the fluid reservoir may be a container, and in othervariations, the fluid reservoir may be an extension of tubing assembly(214), for example, a coil of tubing. As shown in FIG. 2E, the fluidreservoir is connected by the tubing assembly (214) to the multiplexingvalve (206) and the pressure sensor (216), however in other variations,the fluid reservoir may be connected to any number of PL cartridgecomponents in any suitable way. Fluid reservoir (222) and PL cartridgetubing (214) may be manufactured from any of a variety of biocompatiblematerial, such as a variety of polymers (e.g. PVC, polycarbonate,polyethylene, polypropylene, polyurethane, silicone, etc) and/or metalalloys (e.g. stainless steel, Nitinol, cobalt chrome, etc), and mayoptionally be medical grade and sterile. In some variations, tubingassembly (214) and/or reservoir (222) may be pre-molded from polymericor metallic materials. The interior of tubing assembly (214) andreservoir (222) may be formed to facilitate fluid flow. For example, theinterior of the tubing and the reservoir may contain microstructuresthat reduce fluid resistance and drag. The interior may also be coatedwith an agent (e.g. an anti-thrombotic agent) to reduce the likelihoodof tube obstructions, and/or reduce the friction of the internal surfaceof the tube.

Blood Sensor, Air-in-Line Sensor and Humidity Sensor

In some variations, several types of sensors may be used with the PLcartridge, including but not limited to optical sensors. As describedpreviously and shown in FIG. 1, a fluid monitoring system may includesensors that detect the presence of fluid or air in the tubing, orsensors that may discern one fluid from another. For example, in a bloodmonitoring system, there may be blood detectors (180) and air-in-linesensors (178). In other variations, there may be a sensor that detectsspecific analytes in the blood and can detect blood hematocrit.Furthermore, there may be a sensor that determines when whole, undilutedblood has reached a specific point in the fluid circuit. In someembodiments, this sensor may be an optical blood sensor, thoughalternate devices and methods may be used to detect whole, undilutedblood. These sensors are accommodated either within the PL or in thefluid monitoring system external to the cartridge. External sensors(such as optical sensors) may access the environment in PL cartridge andthe fluid sample through access apertures, such as the ones described inFIG. 2C (apertures (218), (220), and (229)). Non-optical sensors thatdetect temperature, humidity, and the like may also be used to measureany number of conditions in the PL cartridge. The data from thesesensors may be transmitted to the control system (185) so that theappropriate parameters may be adjusted according to the changingconditions.

Pressure Sensor

The PL cartridge (200) may also comprise at least one sensor that is indirect contact with the fluid in tubing assembly (214), for example, apressure sensor (216). As shown in FIGS. 2G and 2H, pressure sensor(216) contacts the fluid sample via an aperture (213) of a T-shapetubing connector (215). An O-ring (217) is used to secure the junctionbetween tubing connector (215) and pressure sensor (216) to preventfluid leakage. Latches (221) may be used to connect or couple theT-shape tubing connector (215), O-ring (217) and pressure sensor (216)together, though other methods of secure attachment may be used. Othermethods of providing fluid access to a pressure sensor may be used, suchas bonding the tubing directly to the pressure sensor, or using apressure sensor that may be placed in-line with the tubing. The pressuresensor (216) in FIG. 2G also has an electrical interface (219) thatallows the control system (185) to read an electrical measurement fromthe pressure sensor. The electrical measurement is then correlated to aknown pressure value, by means of the monitor (167), to determine apressure measurement from the PL cartridge. Any interface, mechanical orelectrical, may be used to send a signal that indicates system pressureto the control system. In other variations of the PL cartridge, othertypes of sensors may also utilize direct contact with the fluid in thetubing assembly, for example, electrochemical, pH, and temperaturesensors.

Dispense/Selector Valve

The connectivity between the components of the PL cartridge may beregulated by at least one multiplexing valve. As previously described,the multiplexing valve may be a combination (111) of the fluid selectorvalve (181) and dispense valve (173) shown in FIG. 1. A multiplexingvalve may be adjusted to different configurations to allow theapplication of positive or negative pressure from a pump to distributefluid to various regions of the tubing assembly. In some variations,there may be a plurality of multiplexing valves. One example of amultiplexing valve (206) is illustrated in FIGS. 2I-2M.

Some variations of a multiplexing valve are formed from an assembly ofcomponents. For example, multiplexing valve (206) in FIG. 2J comprises avalve body (240), valve core (250), and valve plug (260). The valve body(240) has plurality of ports that may interface with tubing, forexample, inlet ports (241), (242), (243), and (244), a dispense nozzle(246). Some variations may have an alignment protrusion (248) toprecisely position the valve body with respect to other components ofthe fluid monitoring system. Valve body (240) in FIGS. 2I and 2J istubular, and contains the valve core (250) within its lumen. The valvecore (250) is tubular, and contains a valve plug (260) within its lumen.In some variations of a multiplexing valve assembly, the valve plug(260) is not rotatable within the lumen of the valve core (250), but thevalve core (250) is rotatable within the lumen of the valve body (240).The rotation of the valve core (250) within the valve body determinesthe connectivity between the inlets (241), (242), (243), (244), anddispense nozzle (246).

In certain variations, grooves or conduits on the valve core (250)and/or valve plug (260) form conduits that connected the inlets on thevalve body. For example, in FIG. 2K, groove (252) on the valve coreforms the conduit between inlets (241) and (242). Bores (254 a) and (254b) of valve core (250) are aligned in a fixed position with groove (262)on the valve plug (260) and form a conduit between inlets (243) and(244). The orientation of groove (252) is offset with respect to theconduit formed by bores (254 a), (254 b), and groove (262) so that onlyone fluid connection is made at a time (e.g. either inlets (241) and(242) are connected, or inlets (243) and (244) are connected). However,in other variations of a valve assembly, the orientation of theplurality of conduits with respect to each other may vary such that oneor more connections may be made at a time depending on the particularembodiment of fluid transfer system.

The connectivity between inlets (241) and (242) may be adjusted byrotating the valve core (250), as shown in the Y-Y cross-section of thevalve assembly (250) in FIG. 2L. Inlets (241) and (242) are connectedwhen groove (252) on valve core (250) is positioned to contact bothinlets, such that the groove space is continuous with the inlets. Whenthe groove (252) is in a position where only one or none of the inletsare contacted, then the inlets are not connected. In this variation,inlet (241) is connected to the syringe pump (211), and inlet (242) isconnected to the KVO and flush solution (169), as shown in FIG. 2E. Wheninlets (241) and (242) are connected via groove (252), the syringe pumpis connected to the KVO and flush solution reservoir. In othervariations of the PL cartridge, the inlets may be connected to fluidiccomponents as appropriate.

The connectivity between inlets (243), (244), and dispense nozzle (246)may be adjusted by rotating the valve core (250), as shown in the X-Xcross-section in FIG. 2M. There are three connection states for thismultiplexing function: inlet (243) and inlet (244) are connected, orinlet (243) and dispense nozzle (246) are connected, or none of them areconnected. Note that in this variation of the multiplexing valve (206),during operation, the dispense nozzle (246) may not be connected toinlet (244), however, in other variations, this connection state may beused. The connection state is adjusted by rotating the valve core (250)so that the bores (254 a) and (254 b) (which are aligned with groove(262) in the valve plug) contact the desired inlets. In this variation,inlet (243) is connected to fluid reservoir (222) and inlet (244) isconnected to the fluid access device (171), and the dispense nozzle(246) transfers fluid to the disk assembly. In alternate variations,other fluidic components may be connected to the inlets.

The tip of a dispense nozzle may be any suitable geometry that isconfigured to limit fluid sample adhesion to the dispense nozzlesurface. The tip of the nozzle may be configured to reduce wetting ofthe outside of the nozzle and/or to maintain a sterile fluid path withthe patient or avoid contamination of one or more components of thesystem. FIG. 2M-1 is an enlarged view of the dispense nozzle (246) shownin FIG. 2M. In this variation, the tip (233) of the nozzle (246) ishemispheric, intersecting with a straight edge to form an abrupt sharpedge (231). The sharp edge (231) may break the fluid tension relative tothe hemispheric surface, which may provide a controlled delivery offluid, and reduce loss of fluid or sterility by wetting out. Optionally,the dispense valve and/or nozzle may be coated with an anti-adhesionagent, e.g. an anti-coagulant agent, to ensure effective throughput ofthe fluid sample.

In this variation of the PL cartridge and several of its componentsshown in FIGS. 2E-2M, the multiplexing valve (206) regulates theconnection between the syringe pump (210), KVO and flush solution (169),fluid access device (171), fluid reservoir (222), and dispense nozzle(246), as schematically represented in FIG. 2N. FIG. 2O illustrates anexample of a series of connections (270) that may be made to obtain ablood sample from a patient via fluid access device (171) for glucosetesting. In step (271 a), the system is primed by drawing KVO solution(169) into the syringe (210). Then at step (271 b), the fluid is pumpedfrom the syringe (210) through the reservoir (222) to the patient accessinterface of the tubing. These steps (271 a) and (271 b) be may berepeated until the system is primed. At step (271 c), the KVO solutionis drawn into the syringe. In step (272), the fluid access device (171)and syringe are connected through reservoir (222), and a blood sample isdrawn from the patient towards and some times into the reservoir (222).In this connection configuration, the monitoring system may poll theblood detector to determine if the fluid in the tubing assembly (214) isundiluted blood. If not, then the system may draw more blood from thepatient until the blood detector indicates that the blood sample in thefluid circuit is an undiluted sample. If so, then the monitoring systemmay proceed to step (274). At step (274), the syringe (210) is connectedto the dispense valve through the reservoir (222), and the blood sampleis dispensed for testing by pumping KVO solution towards the reservoir(222) to move the blood sample out of the dispense nozzle. In step(276), the syringe (210) is coupled to the fluid access device (171)through the reservoir (222) and any excess blood and solution mixed withblood that may be in the reservoir is returned to the patient (oralternatively or in part, moved to a waste port through a valve in thetubing path (not shown)). At step (278), more saline fluid is pulledinto the syringe. At step (280), the fluid is pushed from the syringe(210) through the reservoir (222) to the fluid access device at aselected KVO rate until blood is to be drawn again. When blood is to bedrawn again, the system may return to step (272). Other connection andpump sequences may also be used to perform analogous tasks.

Some variations of the multiplexing valve may be rotated to a loadconfiguration after it is manufactured, but before it is used in a fluidmonitoring system for the first time. The load configuration is a valveconfiguration that is not used (and not rotated through) in normaloperation of the fluid monitoring system. During the manufacturingprocess, the multiplexing valve may be imposed into this loadconfiguration using hard stops molded into the valve components. In somevariations of a fluid monitoring system, the PL cartridge may be loadedonly if the multiplexing valve is in the load configuration. In theabsence of a PL cartridge, the fluid monitoring system will transitionto a load state, which is a pre-programmed and known configuration thatwill only interlock with a PL cartridge where the multiplexing valve isalso in a load configuration. If the multiplexing valve of the PLcartridge is not a load configuration, then the cartridge cannot beinstalled in the system. Such a mechanical interlock between themultiplexing valve and the fluid monitoring system in the load state mayact to prevent inappropriate installation of the PL cartridge. Forexample, this feature may prevent the reuse of a PL cartridge, since themultiplexing valve of a used PL cartridge is not in a loadconfiguration. In some variations, the multiplexing valve may contain a“lock-out” feature which prevents the valve from inappropriately beingrotated back to the load configuration after it has been removed fromthe fluid monitoring device.

Fluid Channel Plug

Some variations of a PL cartridge may also comprise a mechanism thatensures that the fluid sample transferred from the dispense nozzle tothe input port of the disk assembly proceeds towards the test substratein the disk assembly, and does not flow back through the fluid channelin the transfer disk. One variation of such a mechanism is a fluidchannel plug (224), shown in FIGS. 2A-2F, which is sized and shaped toobstruct the input port of the transfer disk. The fluid channel plug(224) may be made of any fluid impermeable material, and may be actuatedin any suitable direction. Other mechanisms may also be used to obstructthe input port of the disk assembly. For example, the input port may besealed off with an impermeable membrane, pinched shut with a clip,blocked with a rigid cover, or occluded with an inflatable member.Obstruction of the input port may prevent the spread of any contaminantsbetween the disk assembly and PL cartridge, and may acts to urge theblood sample towards the test substrate.

Disk Assembly

As shown in FIG. 1, some variations of the automated fluid monitoringsystem may comprise a transfer and sensor element, such as disk assembly(188) that receives the fluid sample from the PL cartridge and directsthe fluid to sensors (161) which may be provided in the disk assembly(188). Disk assembly (188) may contain any number of functional modulesthat perform some or all of the tasks used to receive the sample fortesting. For example, the disk assembly may comprise a single cartridgeor housing that receives the sample from the PL cartridge and channelsit to the test substrate, which may have an interface suitable for thecontrol system to read out the test result. In some variations, the diskassembly may comprise two or more functional elements, such asindividual cassettes, drums, cartridges, or disks. Multiple functionalelements may be provided to house and separate components undergoingsterilization or those with other different handling requirements, forexample. Thus, individual components that require sterilization may besterilized, without sterilizing the entire disk assembly. For example, aportion of the disk assembly that may be momentarily in fluid contactwith a patient's circulatory system may be sterilized, but othercomponents of the disk assembly that do not come into fluid contact witha patient may or may not be sterilized. In some examples, limiting oravoiding sterilization of the sensors (or other components) may prolongthe shelf-life or maintain the accuracy of a sensor or a test substrate.A multi-disk assembly may maintain test substrate and/or sensorsensitivity while reducing the risk of contamination to the patient. Anexample of such a disk assembly is illustrated in FIG. 3. In certainvariations, as depicted in FIG. 3, the disk assembly (300) may compriseat least two components, such as a fluid transfer disk (302) and a testsensor disk (304). The transfer disk (302) and the sensor disk (304) areconfigured to work in concert to receive a sample for testing. Thetransfer disk (302) receives the fluid sample from the PL cartridge, andtransfers it to the sensor disk (304) for testing.

Transfer Disk

As shown in FIG. 1, the transfer disk (196) may be a separate componentof the disk assembly (188). A fluid transfer component of the diskassembly, such as the transfer disk (302) shown in FIGS. 4A and 4B, isconfigured to receive the fluid sample from the PL cartridge, and may beparticularly configured to transfer fluid from a sterile source to a nonsterile environment without contaminating the sterile source. In otherembodiments of the disk assembly, the transfer component may also be acassette or cartridge. The transfer disk may comprise a pump and pumpactuator that may be a deformable member. As depicted in FIG. 4A, thetransfer disk (302) comprises a deformable membrane (402), a wipeassembly (404), and a transfer disk structure (406). These threecomponents may be bonded together with an adhesive, where the wipes(405) may be bonded to the outer perimeter of the transfer diskstructure (406). Alternatively, the three components may be bondedtogether by means such as welding or vulcanizing one or more materialsto the other materials. The deformable membrane (402) is overlaid in away to provide a fluid-tight seal to the transfer reservoirs (408), andmay be made of any fluid impermeable, compliant material, such assilicone, latex, urethane, and/or thinly hammered metal alloy orpolymer. In some variations, the transfer reservoirs (408) are arrangedaround the outer circumference of the transfer disk structure (406), andthe membrane is sized and shaped to cover the open side of the transferreservoirs (408), which may form individual fluid displacement elementsoperatively coupled to each reservoir (408). The transfer disk structure(406) is made of molded acrylic, but may be made of any material withsimilar structural and optical properties. Wipes (405) may be evenlyspaced around the outer edge of transfer disk structure (406), andarranged to contact the dispense nozzle (246) during use. The transferdisk structure (406) may comprise an interface that allows the controlsystem to read out from the test sensors of the sensor disk, forexample, apertures (410) may be sized and positioned according to thesize and positions of the test sensors on the sensor disk, which may beadjacent to the transfer disk. Apertures (412 a-b), indentation (413),and latches (415) are structures that may be used to align the transferdisk to the other components of the fluid monitoring system, and tosecure and lock the transfer disk in place for use. These features willbe described in detail below.

As shown in FIG. 1, transfer disk (196) may comprise a plurality offluid sample cavities (189) that separate and transport a fluid sample.One variation of a transfer disk comprises a transfer disk structure(406) as shown in FIG. 4C. Transfer disk structure (406) may comprise aplurality of transfer reservoirs (408), such as the 25 transferreservoirs, but in other variations, any other number of transferreservoirs may be provided, including but not limited to at least (or nomore than) about 5, about 10, about 15, about 20, or about 30 transferreservoirs. Reservoirs may be disposed in a circular pattern on the diskor may be disposed in 2 or more coaxial circular patterns so thatmultiple reservoirs exist at 2 or more radial positions along eachradius line, thus increasing the capacity of reservoirs on the disk bytwo fold or three fold. Each transfer reservoir (408) may have an inlet(416), which receives the fluid sample from the PL cartridge dispensenozzle (246), and an outlet (418) which allows the sample to betransferred to the sensor disk for testing, as shown in FIGS. 4D and 4E.Inlet (416) and outlet (418) may be openings or channels. In somevariations, the transfer reservoir may also comprise an outlet neck(417), which may be a shallow channel from the transfer reservoir to theoutlet. Optionally, transfer reservoir (408) may comprise a plurality ofridges (420) that discourages fluid adhesion to the surface of thetransfer reservoir, thus facilitating the movement of the fluid frominlet (416) to outlet (418). The ridges (420) may be arranged in series(in any orientation) along the fluid flow from the inlet (416) to theoutlet (418). For example, the ridges (420) may be oriented parallel tothe fluid flow into the reservoir. The fluid flow from the inlet to theoutlet may vary depending on the orientation of the transfer disk. Forexample, in some variations of a fluid monitoring device, the transferdisk may be mounted vertically, i.e. on its side. In this variation, ifthe fluid sample is dispensed to a transfer reservoir at location (419)shown in FIG. 4C, the fluid sample entering the inlet would need to beurged upward towards the outlet. Alternatively, if the fluid sample isdispensed to a transfer reservoir at location (421), the fluid sampleentering the inlet would flow downward towards the outlet due togravity. In some variations, the transfer disk may be mountedhorizontally. In some variations of a horizontally mounted disk, thereservoir and fluid channels would be positioned so that fluid enteringthe inlet would need to be urged across the transfer reservoir in orderto exit through the outlet.

The fluid sample may be transferred from the inlet (416) to the outlet(418) in various ways. In some variations, the transfer may not takeplace until after the dispensing of the fluid ceases entirely, i.e.there is no fluid that connects the PL cartridge and/or dispense nozzleto the disk assembly. A number of variations may be used to help move asample from inlet (416) into the transfer reservoir. For example, thetransfer reservoir (408) (or the portion of the disk assembly) thatcontains the fluid sample may be tilted, allowing the sample is directedto the outlet (418) by gravity feed. Alternatively, the transferreservoir (408) may be made of a material that facilitates capillaryaction. The direction of the capillary action may be configured bymachining different micro patterns on the surface of the transferreservoir that allows fluid migration in one direction but not in theopposite direction. In some variations, this material may besubstantially contacted with the test substrate, allowing the fluid tobe conveyed by capillary action entirely within the material. Fluid mayalso be drawn towards the outlet (418) by setting up a pressure gradientacross the transfer reservoir (408), such that the outlet (418) is in aregion of lower pressure. Pressure gradients may be created through theuse of a vacuum bulb, drawing the fluid into the transfer reservoir, andexpelling the fluid towards the outlet. For example, it may urge, push,or direct the fluid towards the outlet with a fluid displacing elementor fluid directing element. Other methods of directing the fluid sampleto the transfer reservoir outlet may utilize deformable or displaceablestructures. For example, the transfer reservoirs made be made of adeformable material, such as silicone or a sheet of malleable metalalloy, and tubular shaped, so once the fluid has been dispensed anddissociated from the PL cartridge, the tubular transfer reservoir ispinched shut, and the pinching mechanism gradually moves towards theoutlet, essentially “squeezing” the fluid sample to the outlet (418). Inother embodiments, the fluid may be urged through the transfer reservoirby a slidable seal or piston, which may act to pressurize the transferreservoir cavity. In another variation, the volume of the transferreservoir (408) may be adjusted, e.g. from large to small, to displacethe sample fluid towards the outlet neck (417). The volume of a transferreservoir may be changed by constricting or dilating the transferreservoir lumen and/or introducing an external element that displaces asufficient volume in the transfer reservoir that forces the fluid sampleto move towards the outlet. One example is shown in FIGS. 4F and 4G. Thedeformable membrane (402) is sealed across the transfer reservoir (408)which creates a liquid-tight enclosure. Once a desired quantity of fluidis deposited into the transfer reservoir (408), the membrane (402) isdeformed with a piston (476). The deformation in the membrane (402)created by the piston (476) acts to displace the fluid into the outlet(418). The initial volume of the transfer reservoir (408) may be of anysuitable quantity, for example, between approximately 1.2-10.0 μL, orapproximately 1.0-100 μL, or approximately 1.0 μL to more than 100 μL,however, when the membrane (402) is deformed, the volume of the transferreservoir is reduced from the initial volume. The volume of the transferreservoir before and during membrane deformation may vary widely. Thismethod of fluid transfer may allow for a greater degree of flow control(as compared to gravity feed or capillary action) and may be done morerapidly (as compared to “squeezing” the fluid in a tubular transferreservoir). In alternate embodiments, a displaceable seal or piston witha generally fixed configuration may be provided to push the fluid sampleout of the transfer reservoir. Furthermore, positioning the outlet neck(417) at a higher plane than the inlet (416) buffers the downstreamsensor substrate from fluid overflow, which allows the control system(185) additional time to remedy the overflow condition. The inlet (416)may be occluded, covered, sealed or blocked to prevent the fluid samplecontained in the transfer reservoir from flowing backwards when thepiston (476) acts on the membrane (402). For instance, the fluidtransfer plug (224) shown in FIGS. 2A-2E may be used to block the inlet(416). Other suitable means of occluding the inlet may also be used, forexample, the inlet may be constricted by a clip, or sealed off with athin film material or flap.

The membrane (402) may be shaped such that a deformation in the membrane(402) will displace the fluid sample within the transfer reservoir(408). In some configurations, the membrane (402) may have a pluralityof folds and/or creases, which may allow for a greater degree ofmembrane compression and fluid displacement. For example, the folds maybe evenly formed in a pleated configuration, but may also assume anysuitable geometry. In other variations, the membrane (402) is stretchedover the transfer reservoir (408) with a certain degree of tension, withfew if any folds or creases. This configuration may reduce or minimizethe surface area of the membrane that contacts the fluid sample, whichmay increase the quantity of fluid that is transferred to the sensorsubstrate. Each portion of the membrane is isolated from each other bychemical bonds, mechanical bonds, or a combination thereof, orinterference plastic fit parts to ensure that the fluid within eachreservoir is maintained within that reservoir without leaking ortransferring to other reservoir. These features may act to isolate thesample to one and only one transfer reservoir. This may reduce oreliminate cross contamination between samples.

The fluid input channel to transfer reservoir (408) may be any shape orsize that efficiently accepts a fluid sample. A variation of fluid inputchannel is shown in FIGS. 4I and 4K. The fluid input channel comprisesan input aperture (424) that is connected to a bore (423) shown in FIG.4I. Some variations of a fluid input channel may have a tapered inputaperture (424) to better mate with the shape of the dispense nozzle ofthe PL cartridge, which may funnel fluid into the transfer reservoir(408) more efficiently, however the shape and size of the input aperture(424) may be varied according to the characteristics of the systemand/or fluid viscosity. The size and shape of the input aperture (424)may also facilitate the dissociation of the fluid from the dispensenozzle from the fluid in bore (423). Breaking the fluid connectionbetween the dispense nozzle and the fluid input channel may reduce therisk that contamination which may have entered the transfer disk fromother sources is then transferred to the patient. Optionally, thesurface of the input aperture (424) and bore (423) may be coated toprevent the fluid from adhering to the surface. The coating may be ananti-coagulant agent, surfactant, or charge-neutral coating that mayreduce the influence of electrostatic forces on fluid flow.

FIG. 4J depicts section B-B taken across the transfer reservoir (408)and outlet neck (417) shown in FIG. 4H. In a horizontal position (suchas the orientation shown in FIG. 4J), the outlet neck and outlet of thetransfer reservoir (408) may be located at a higher plane than the inlet(416). Such an arrangement may prevent a direct and immediate fluidflow-through from the inlet to the outlet. In a vertical position, wherethe outlet neck (417) points up and the inlet (416) points down, a fluidsample entering the inlet would be prevented from directly andimmediately flowing through to the outlet (418). In these arrangements,the transfer reservoir acts as a buffer intermediate between the inletand outlet, and may allow for increased control of fluid flow betweenthe transfer disk and sensor disk. Features that allow for preciseregulation of the fluid flow may reduce the possibility of a continuousfluid connection from the sensor disk to the transfer disk to thepatient. This may safeguard the patient against contamination from anynon-sterile components of the disk assembly.

Transfer reservoirs may also comprise a fluid detector to indicate whenthe transfer reservoir has reached a maximum or minimum fill level. Avariety of sensors may be used, such as optically reflective,electrically conductive, or capacitive sensors. Certain variations oftransfer reservoirs (408) are formed of molded acrylic, which allowssensors optical access to the contents within the transfer reservoir.For example, as shown in FIGS. 4I and 4L, total internal reflectionminors (414) are molded into the transfer disk structure, and maychannel the optical characteristics of the transfer reservoir contentsto a sensor that detects for the presence or absence of fluids. In somevariations, an infrared beam enters into the transfer disk and isreflected back to the transfer reservoir along a light path, for examplelight path (427), until a fluid (such as blood) interferes with thebeam. In this embodiment, as shown in FIG. 4L, the infrared beam emitterand receiver may be located on the fluid monitoring system, directlyacross from the total internal reflection minors in the transferreservoir, configured to transmit and receive light, e.g. infrared,along light path (427). Some embodiments of an infrared sensor candetect quantities of fluid between about 50 μL to about 80 μL, butsensors with other ranges of fluid sensitivity may also be used. Fluidsensor output may be used as a feedback signal to the control system(185) to regulate various aspects of the fluid monitoring system, suchas adjusting the fluid flow and quantity (e.g. to prevent under fill andoverfill conditions), and to signal if fluid is unexpectedly in thetransfer reservoir.

As shown in FIGS. 4B and 4H, the transfer disk structure (406) maycomprise a number of alignment features, such as notches, interlockingstructures, apertures, and protrusions. Appropriate alignment of thetransfer disk with respect to the other components of the fluidmonitoring system may ensure precise fluid transfer from one componentto the other. Such alignment features may also be used to provideclearance between the individual components of the disk assembly, andmay include locking mechanisms to secure one component to another. Forexample, apertures (412 a) and (412 b) shown in FIG. 4B on the transferdisk (302) may be aligned to protrusions on other parts of the fluidmonitoring system, so that the monitoring system can precisely dispensethe fluid sample, locate the sensor outputs, and correctly index theindividual transfer reservoir units on the transfer disk. Indentation(413) may be sized and shaped to mate with other components of themonitoring system to ensure consistent and precise alignment. Latches(415) may be mechanically interlocked with complementary structures,e.g. notches, on the monitoring system, to secure and lock the transferdisk to the overall system. Transfer disk structure (406) may alsocomprise alignment aperture (426) that mates with the alignmentprotrusion (248) to ensure precise positioning of the dispense nozzle(246) into input aperture (424). The transfer disk structure (406) mayalso have an alignment notch (422) to mate with an alignment protrusionon the PL cartridge to precisely position dispense nozzle (246) incontact with wipe (405) in between dispense cycles. The transfer disk(302) may have any number and variety of alignment features to preciselyposition and secure it to the fluid monitoring system.

The transfer disk (302) may comprise cleaning pads or wipes (405)similar to those shown in FIG. 4H to wick away excess fluid from thedispense nozzle (246) in between dispense cycles. The wipes (405) may bemade of any absorbent material, for example, a polyester/cellulosenon-woven blend, which has a high affinity for the fluid that is beingmonitored so that the fluid may be wicked away quickly and evenly. Thewipes (405) may be positioned or shaped in any way that optimizes itscontact with the dispense nozzle (246). For example, some wipes (405)may comprise protrusions and/or micro structures to increase surfacearea contact with the dispense nozzle, the protrusions may be shaped tobe complementary to the shape of the dispense nozzle. In somevariations, the wipe (405) may be positioned on a mechanism that can beactuated to wipe the dispense nozzle, for example, the wipe may be movedlaterally across the dispense nozzle, or plunged into and out of thelumen of the nozzle to absorb excess fluid. In other variations, wipesmay contact the dispense nozzle without any lateral movement, i.e. thewipe may “blot” the dispense nozzle to wick away excess fluid. Excessfluid may contaminate any sterile components in the PL cartridge ortransfer disk, as well as possibly skewing the test results of laterfluid samples. In the case where blood is the fluid that is monitored,excess blood on the dispense nozzle (246) may clot and occlude thetransfer of latter blood samples for testing, and may contaminate thelatter samples which may result in an inaccurate test result.

Sensor Disk

As described in FIG. 1, sensor disk (190) may be a separate componentfrom the transfer disk (196), but configured to interface with thetransfer disk (196) via a mechanical lock. Some variations of the diskassembly (300) shown in FIG. 3 may comprise a sensor element, such assensor disk (304). In other embodiments of the disk assembly, the sensorcomponent may also be any assembly enclosed in a housing, or may be anassembly of multiple cassettes, cartridges, or disks. FIG. 5A depictsone variation of a sensor disk (304). Sensor disk (304) includes aplurality of test substrates (each configured to receive a sample)and/or test sensors (each configured and analyze a fluid when it mixeswith chemicals, reagents or interacts with other components of a testsensor or test substrate). The sensor may be electrical,electrochemical, optical, or optoelectronic, for example. In somevariations, sensor disk retains an array of test sensors such that eachtest sensor is configured to receive a fluid sample from a singletransfer reservoir. A sensor disk (304) may comprise test sensors (502),a sensor disk structure (504), and an absorbent lamina (506). The sensordisk structure (504) is made of molded acrylic, but may be made of anymaterial with similar structural and optical properties. Some or allcomponents of the sensor disk (304) may be sterilized, however, in somevariations, the test sensors (502) may not be able to be sterilizedwithout compromising shelf-life, reliability, and/or accuracy. Somevariations of the sensor disk (304) may comprise absorbent lamina (506)to retain any excess fluid that may be transferred from the transferreservoir to the sensor disk. This may prevent cross-contaminationbetween test sensors (502). The absorbent lamina (506) may be comprisedof any absorbent material (505), for example a polyester/cellulosenon-woven blend, and be secured by a rigid structure (507) that is sizedand shaped to fit with the sensor disk structure (504). The sensor diskstructure (504) comprises apertures that allow the fluid sample tocontact the absorbent material (505), for quick and even absorption,without contacting the transfer reservoir outlet or test substrate ofother test sensors (502).

Certain types of test sensors (502) may be maintained in a relativelymoisture-free environment to extend shelf-life and test accuracy. Somevariations of a sensor disk (304) may comprise desiccating features, forexample, a desiccating material (508) and a desiccant cap (510) tomaintain a moisture-free environment in the sensor disk. The desiccantmaterial, such as molecular sieve, silica gel, or any clay-basedgranular desiccant, may be contained in the airspace between thedesiccant sieve (508) and desiccant cap (510). The quantity and type ofdesiccant to include may be determined by the anticipated moistureinflux that the sensor disk may be expose to during its course of itsshelf-life and use. Some variations of the sensor disk (304) may alsocomprise a humidity sensor (167 j), as depicted in FIG. 1, thatcommunicates humidity data to the control system (185) so that the testsensor reading may be adjusted according to the humidity in the sensordisk (304). For example, the readings from glucose test sensors may needto be adjusted according to the humidity level over time. Excessivelyhumid or excessively dry sensor disk environments may render the testsensors (502) inaccurate, and the control system (185) may instruct theuser to replace the sensor disk (304).

RFID Feature

As described previously, some variations of the sensor disk (304) mayalso comprise machine readable indicia that may be relayed to thecontrol system (185) using an indicia reader. The indicia reader may be,for example, a barcode reader, a radiofrequency identification (RFID)reader, and/or an electrical connection to an EPROM or other chiplocated on the sensor disk (304). For example, as shown in FIG. 5B, thesensor disk may comprise an RFID chip (512) that communicates with thecontrol system through an RFID serial interface. The RFID chip maycontain information, such as the disk type, manufacturing date and time(including batch tracking numers, factory and operation data), testsensor codes (indicating test sensor quantity, type and expirationdate), calibration codes, and sensor disk expiration date. Data may alsobe written to the RFID. In some embodiments, the RFID may be secured sothat it can only be written to by a specific type of fluid monitoringsystem, and may only be written to once, and optionally encrypted. Thetypes of data that may be written to an RFID by the monitoring systemmay be the first time of use, any indicators and identifiers ofmalfunctioning or adverse events (e.g. damage sustained during use),temperature and humidity conditions under which the sensor disk wasused. Patient data may also be written to the RFID. In some cases, thedata on the RFID may indicate to the fluid monitoring system that thesensor disk is defective or error-prone, and should be replaced. TheRFID (512) may also indicate to the control system if the sensor disk isproperly installed, aligned, and locked into place. The RFID may also beused to relay calibration curves and other analysis or configurationdata to the controller in multiple analyte systems. For example, therotational/axial position of different analyte sensors may be stored inthe RFID so the monitoring system can coordinate the application ofappropriate firmware, analytical algorithms, or calibration data to eachtype of sensor.

Sensor Disk Structure

Some variations of the sensor disk structure (504) may comprise severalalignment features as shown in FIG. 5C. Protrusions or pins may passthrough apertures (528 a) and (528 b) to align components of the sensordisk (304) to the fluid monitoring system. The sensor disk structure(504) may also comprise a protrusion (533) that may engage the sensordisk (304) with other disk components, e.g. the transfer disk. To engagewith other disk assembly components, such as the transfer disk, theprotrusion (533) for each disk must be sized and shaped to mate with thegrooves and protrusions of the other disks. Additionally, thesealignment features may also comprise locking features, such as hooks orsnap locks (531 a-c), which secure the sensor disk (304) to the transferdisk. These locking features may reversibly or irreversibly engage otherdisk assembly components.

The sensor disk structure (504) may comprise additional apertures forpurposes other than alignment, as shown in FIGS. 5D and 5E. For example,aperture (530) is arrayed throughout the sensor disk structure (504) toprovide ventilation to facilitate the capillary of the test sensor.Apertures of other sizes and shapes may aid in the precise manufacturingof the sensor disk structure (504), the loading of sensors (502), andmay also provide exposure to a desiccant. For example, aperture (524)may expose underlying layers of the sensor disk (304), such as theabsorbent material (505), so that the absorbent material (505) may becontacted by fluid that is present in aperture (524).

The sensor disk (304) may be configured to retain 25 test sensors (502)as shown in FIG. 5F, but in other embodiments, any other number ofsensors may be retained, include but not limited to at least (or no morethan) about 5, about 10, about 15, about 20, or about 30 test sensors(502). Additionally, test sensors may be disposed on the sensor disk inmultiple coaxial circular patters to double or triple the number ofsensors to match a higher density transfer disk as described above. Eachtest sensor (502) is retained in a semi-enclosed subunit (514) of thesensor disk structure (504). Each sensor disk subunit (514) is separatedfrom the adjacent subunit by a wall (515), which may be of sufficientheight to prevent fluid transfer (cross-contamination) between subunits,as shown in FIG. 5H. The test sensors (502) are secured within eachsensor disk subunit (514) by several retainer protrusions (516). Asshown in FIG. 5G, there are also alignment protrusions (518) that ensurethe position of the test sensor (502). In some variations, the alignmentprotrusion (518) may be sized and shaped to fit a complementary groove(519) in the test sensor (502). For example, a cylindrical alignmentprotrusion (518) may be used to align a sensor (502) with asemi-circular groove (519).

Test sensors (502) may comprise a sensor substrate (503) and electrodecontacts (532), depicted in FIGS. 5I and 5J. The sensor substrate (503)reacts with the fluid sample, which forms an end product that isindicative of the quantity of the analyte in the sample. Thismeasurement may be communicated to the control system via electrodecontacts (532). For example, blood glucose sensors may receive bloodwhich reacts with the sensor substrate (503) reagent, and the monitoringsystem may analyze the glucose content in the blood sample via theelectrodes (532). Sensors that detect different analytes may havedifferent test substrates and electrode configurations, and the sensordisk structure (504) may be modified to accommodate the differentlocation of the sensor substrate (503) and electrodes (532). Somevariations of sensors, such as certain glucose sensors, may provideadditional data to the control system. For example, it may comprise anunder-fill or over-fill detection unit that indicates to the controlsystem if a sufficient fluid sample has been received by the substrate.

Each sensor disk structure subunit (514) comprises a fluid samplereceiving area (520), depicted in FIG. 5I. Receiving area (520)comprises a groove (522) and an aperture (524). Aperture (524) may opento expose absorbent material (505). In FIG. 5I, the sensor substrate(503) is oriented over the groove (502), however the sensor substratemay be oriented in any way that is suitable for receiving blood from thetransfer disk. In some variations of the sensor disk structure (504),groove (522) may be a drain that captures a portion of the fluid samplefrom the transfer disk outlet, and aperture (524) which exposesabsorbent material (505) may wick up any overflow fluid from the groove(522). Positioning the sensor substrate (503) over the groove (522) maypermit immediate access to the transferred fluid sample, before thefluid sample is absorbed by material (505). In some variations, the testsensor substrate (503) is not in direct contact with groove (522), andtakes up the dispensed fluid sample by capillary action.

The shelf-life of some types of test sensor substrates are sensitive tohumidity and/or temperature. Some variations of a fluid monitoringsystem may comprise at least one humidity sensor, as shown in FIG. 1(for example, humidity sensor (167 j)), near the installation site ofthe sensor disk. However, in other variations of a fluid monitoringsystem, the humidity sensor(s) may be located anywhere in the system,for example, away from the installation site of the sensor disk.Humidity sensors may be optionally provided along the walls of thesensor disk or the transfer disk. A variety of humidity sensors may beused, for example, chemical, capacitive, resistive, or thermalconductivity humidity sensors. The humidity sensors may measure absolutehumidity, relative humidity, or dew point, and may integrate any suchmeasurements over time to evaluate the moisture content in the air. Forexample, a chemical humidity indicator, such as a silica gel desiccant,may indicate the cumulative quantity of moisture in the air by changingcolor. Other humidity sensors may communicate the moisture measurementto the control system (185) through an electrical interface, where thecontrol system may compute the expected test sensor life based on thehumidity measurement. In some cases where the humidity measurement maybe affected by temperature, a temperature indicator may also be includedin the system, or integrated with the humidity sensor. In certainembodiments, sensor life can be plotted against relative humidity (% RH)integrated over time, as shown in FIG. 5K. Temperature may also impact asensor's shelf-life, and plots similar to that shown in FIG. 5K may begenerated at different temperatures. The control system may monitor thehumidity of the sensor disk before use, and integrate the humidity levelover time, where the integration is weighted depending on thesensitivity at the different humidity levels. At a given humidity, therate of sensor life degradation may be determined according to the plotin FIG. 5K. For example, as each hour passes (or any time unit), thecontrol system may poll (at any suitable frequency) the humiditymeasurement, and adjust its evaluation of sensor life based on thecurrent humidity measurement. In some cases, the relationship between %RH and sensor life may be linear, while in other cases, it is non-linear(e.g. may contain a series of linear regions where the linearitycoefficient varies with relative humidity, or may be non-linear acrossthe entire range of % RH). For example, the shelf-life of a sensor at70% relative humidity (% RH) may be about 20 times shorter than at 25%RH. If there is a non-negligible temperature shift in the course of theuse of the sensors, the relationship between sensor life and % RH may bealtered, e.g. % RH axis shift, and/or linearity coefficient shift, etc,and the computation for the expected shelf-life may incorporate thistemperature effect. An example of a humidity integration routine (550)the system may perform to evaluate test sensor life is depicted in FIG.5L. After the sensor disk is installed in the system (552), theintegrated humidity level is reset to zero and the first humiditymeasurement is taken (554, 556). Another humidity measurement isperformed after a certain period of time. The control system thendetermines how much time has elapsed since the previous humiditymeasurement (558). Based on the humidity measurement, the sensitivityfactor is computed based on a plot of sensor life as a function ofhumidity, shown in FIG. 5K. The sensitivity factor at a given % RH is100% divided by total sensor life at that % RH. The routine (550) thencomputes the product of current humidity measurement, elapsed time, andsensitivity factor (562). This result is added to the integratedhumidity level (which is initially zero) in step (564). At that point,the routine will compare the integrated humidity level against themaximum limit, e.g. at or around 100% (566). If the integrated humidityis below the maximum limit, then the routine will loops back to step(556) and iterate at a pre-determined frequency, e.g. once per minute,once per 10 minutes, etc, until the sensor life expires due to elapsedtime or increased humidity. If the integrated humidity is near 100%, thesystem may issue a warning signal to the user. When the integratedhumidity is at or exceeds 100%, then the sensor will be consideredinaccurate and/or unfit for use, since the expected shelf-life has beenexceeded (which may be due to, for example, elapsed time, or changes inhumidity or temperature). Once the sensors have exceeded theirshelf-life, the system may issue an alert or alarm to remove or discardthe sensor disk. Other computational methods and routines may be used todynamically update the expected shelf-life of the sensors. The controlsystem may poll the humidity sensor when the sensor disk is installedand determine if the sensor disk is suitable for use, given the measuredhumidity (and temperature, for certain embodiments). If the sensor diskis determined to be unsuitable for use, the system may issue an alarm toremove the sensor disk. The relative humidity may also be plottedagainst other sensor factors, such as sensitivity, accuracy, and/orprecision. For example, a plot similar to FIG. 5K may be generated thatrelates % RH to sensor sensitivity, which may be used to adjust thereadings from the sensors to compensate for shifts in humidity and/ortemperature. In certain embodiments, humidity sensors as described aboveare provided in a plurality of locations throughout the fluid monitoringsystem, such as the PL cartridge, the transfer disk, the sensor disk,etc. If excessive humidity is a result of moisture that originates fromwithin the system, a plurality of humidity sensors in the system mayprovide sufficient information to the control system to localize thesource of humidity and flag an indicator to remove the moisture source.

Interface Between Transfer Disk and Sensor Disk

As described previously, in some variations of a fluid monitoringdevice, the disk assembly may comprise a transfer element and a sensorelement, either enclosed in a single housing, or separated as individualcassettes, cartridges, or disks. The variation of disk assembly shown inFIG. 6A comprises a transfer disk and a sensor disk which are securedand actuated together. FIG. 6A depicts features such as slots (602),apertures (606), and protrusions (604) that are configured to secure thetransfer disk and sensor disk together. Either or both the transfer diskand sensor disk may be sterilized individually or in combination. Thetransfer disk and the sensor disk may be permanently secured together,and may be removed from the system and disposed between patients. Thesensor disk may be disposed of when the sensors have expired (i.e.exceeded their shelf-life) or all of the sensors have been used. Eitherthe sensor disk or transfer disk may be disposed of (individually ortogether) if contaminated or previously used.

In certain variations of the disk assembly (300) as shown in FIG. 6B,the outer edge of the transfer disk (302) juts out or protrudes from thesensor disk (304). The gap (613) provides clearance for alignmentfeatures. Edge (621 a) on the transfer disk articulates with edge (621b) on the sensor disk, which aligns the two disks and ensures that thereis adequate clearance between the two disks. In the variation shown inFIGS. 6B and 6C, there is sufficient clearance such that no portion ofthe transfer disk contacts the test sensors (502). In FIG. 6C, theoutlet (418) from the transfer disk (302) is positioned directly over,but not touching, the sensor substrate (503), separated by gap (623).The gap (623) may be between the transfer disk and the sensor disk for aportion of the fluid path to a test location of the test substrate ortest sensor. The disk assembly (300) may also include an accessinterface for the system to contact the test sensor electrodes (532). Insome variations, an aperture is provided for external reading elementsto access electrodes (532), while in other variations, the electrodereading elements may remain entirely internal to the disk assembly(300). As shown in FIGS. 6B and 6C, the test sensor (502) is not incontact with the transfer disk (302). The disk assembly (300) maycomprise a membrane (402) depicted in FIGS. 6B-6D. In some variations,the membrane (402) is silicone, and stretched over the perimeter of thedisk assembly (300) such that the membrane forms a fluid-tight seal withthe transfer disk transfer reservoir (408), however, the membrane (402)may be made of any other material with similar properties, such as amalleable metal alloy. The membrane (402) may have varying degrees ofelasticity and may be stretched over the transfer reservoir (408) withvarying degrees of tension.

Interface Between Disk Assembly and Patient Line Cartridge

In some fluid monitoring systems, the disk assembly (300) is installedwith minimal contact with other system elements as shown in FIG. 7. Forexample, disk assembly (300) may be installed to maintain an air spaceor gap between the alignment aperture (426) and alignment protrusion(248) of the PL cartridge (200). This ensures that the dispense nozzle(246) of PL cartridge and the inlet of the disk assembly (300) (notshown in FIG. 7) also maintain an air space. Such a load configurationmay be useful for some variations to maintain the sterility of eitherthe PL cartridge (200) or the disk assembly (300). Other loadconfigurations may be used as appropriate for other disk assemblies andPL cartridges, depending on the degree of sterility that is desired.

Some variations of a fluid monitoring system may include mechanisms thatprevent the installation and use of an inappropriate PL cartridge (200),such as an incompatible part, or a previously used PL cartridge. Forexample, when there is no PL cartridge the fluid monitoring system, thealignment and/or lock features of the fluid monitoring system may be ina “load” configuration. Only PL cartridges that are also in a matching“load” configuration can be installed in the system. This mechanism maybe implemented in the dispense valve, where the “load” configuration isone that is not used during the operation of the PL cartridge. Other subcomponents may carry out this lock-out function.

Operational Configurations

Once the PL cartridge and disk assembly have been installed into thesystem according to the various alignment and locking features, thesystem may undergo an initialization and/or diagnostic procedure. Theinitialization or diagnostic procedure may involve polling and testingall system sensors (temperature, humidity, pressure, air-in-linedetector, blood detector, etc) to ensure that every sensor is properlycalibrated, installed, and initialized. Initialization may also includepriming the tubing system within the PL cartridge, for instance,perfusing a cleaning solution or saline into all the tubing. Thisperfusion step may serve to reduce or eliminate the air in tubing andmay rinse away any residual manufacturing agent. The perfusate may thenbe flushed out of the system through a waste portal. The initializationprocedure may also include reading the RFID components of the PLcartridge and disk assembly as previously described. The informationread from the RFID components may be incorporated by the control systemto adjust the operation of the fluid monitoring system, and may alsoconfirm that the PL cartridge and disk assembly have been properlyaligned and installed. The control system may also have data from a lookup table, e.g. provided by disk assembler, manufacturer or transporterconcerning lot numbers, initial lot calibration information, dates ofassembly, production or transport information, etc. This information maybe downloadable or otherwise provided to a user of the instrument.

Dispense Configuration

After the initialization procedure has successfully completed, PLcartridge (200) and disk assembly (300) may be placed in a fluiddispense configuration (803), as shown in FIG. 8A. In the dispenseconfiguration (803), the alignment protrusion (248) on the PL dispensevalve is inserted in the alignment aperture (426), which ensures thatthe dispense nozzle positioned to deliver a fluid sample to the transferdisk inlet (not shown) to the transfer disk transfer reservoir (408).Once such alignment is confirmed, the control system may signal to thePL cartridge to dispense a fluid sample to the transfer reservoir (408)of disk assembly (300). The asterisk in FIGS. 8A-8D marks the transferreservoir that received the sample in FIG. 8A. The fluid channel plug(224) may or may not be aligned with transfer disk inlet. In dispenseconfiguration (803), the PL cartridge (200) and the disk assembly (300)may be in close proximity (812) to each other.

Withdrawal Configuration

After a desired quantity of fluid has been dispensed to the diskassembly (300), as sensed by a fluid sensor in the system, e.g. withinthe transfer disk transfer reservoir (408), the control system (185) mayissue a command to the PL cartridge to cease the fluid flow. Then, thePL cartridge (200) and/or the disk assembly (300) may be manipulated sothat the distance between then is increased (813). In the withdrawconfiguration (804), the distance (813) may be large enough to separateany fluid connection that may remain between the PL cartridge and diskassembly after the PL cartridge has ceased the fluid flow. In somevariations, the distance between the PL cartridge and disk assembly inthe withdraw configuration (804) may be small, but large enough so thatthe individual components may be advanced or rotated without impactingthe other. In the withdraw configuration (804), the fluid channel plug(224) may not be in contact with the disk assembly (300).

Indexing Intermediate Configuration

Some variations may have an indexing intermediate configuration (805)where the disk assembly (300) is advanced with respect to the dispensenozzle. An example of a position in the intermediate configuration (805)is shown in FIG. 8C. This may be achieved by rotating, translating, orpivoting the disk assembly (300), and/or manipulating the PL cartridge,so that the dispense nozzle (246) and alignment apertures (426) is movedtowards a transfer reservoir (408) other than the one just accessed. Thedistance (815) between the PL cartridge and disk assembly may be largeenough so that the disk assembly and PL cartridge may be rotatedseparately without substantial contact. The fluid channel plug (224) maynot be in contact with the disk assembly (300). The indexingintermediate configuration (805) may rotate the disk assembly (300) anynumber of steps to any transfer reservoir (408), consecutive orotherwise, on the disk assembly. For example, the disk assembly (300)may be rotated clockwise or counterclockwise, in any order, and anynumber of degrees (e.g. about 10°, 13°, 25°, etc). In some fluidmonitoring systems, the control system (185) may maintain a lookup tableto track which transfer reservoirs have already been accessed, and maybe programmed to access to a transfer reservoir only once. The sequenceand degree of rotation may be determined by the positioning and numberof transfer reservoirs on the disk assembly. In certain variations, thesequence and degree of rotation may prevent the contamination of wipes.The lookup table may also contain information about the type of sensorlocated at each index position, and based upon user input, (or uponinformation in a look up table accessible by the controller andcorresponding to RFID lot number) may advance the disk assembly so thatthe fluid is dispensed to the transfer reservoir that transfers thesample to the desired sensor type.

Wipe Configuration

In some variations of a fluid monitoring system, a wipe configuration(806) may follow the index configuration (805), as shown in FIG. 8D. Thewipe configuration (806) that positions the alignment protrusion (248)in a notch (818), which may also position the dispense nozzle in contactwith a wipe (not shown). In wipe configuration (806), the fluid channelplug (224) may be occluding the inlet to a transfer reservoir (408) thatmay contain a fluid sample, preventing any back flow of fluid from thetransfer reservoir. In this configuration (806), the fluid sample may betransferred to the test sensor substrate by any mechanism, for example,pumping, pushing, or gravity feed. The distance between the PL cartridgeand disk assembly may be reduced from the previous configuration (e.g.the withdraw (804) and/or index intermediate (805) configuration), suchthat the alignment protrusion (248) is fully inserted into notch (818),and the dispense nozzle is in substantial contact with a wipe (notshown). The control system (185) may maintain a lookup table that trackswhich wipes have been previously used.

Fluid Transfer Path

As depicted in FIG. 9A, the control system (185) may regulate the timingand fluid flow in various stages in the PL cartridge and disk assembly.After the fluid sample (e.g. blood) is obtained from the source (e.g. apatient), the sample is first accumulated in the PL cartridge (200), forexample, in fluid channels or a reservoir. The control system (185) mayhold the sample in the PL cartridge (200) as long as desired, and maywithhold the sample from testing if sample contamination is suspected.When the control system (185) configures the disk assembly to receivethe sample, the sample may be dispensed from the dispense nozzle (246)to the transfer disk (302), where it may enter a transfer reservoir(408) via an inlet (416). Once the transfer reservoir (408) has receiveda sufficient quantity of fluid sample, the control system (185) may thenstop the fluid flow from the PL cartridge (200) to the transferreservoir (408), by closing the dispense valve (206) or adjusting thepressure in the PL cartridge (e.g. by adjusting the syringe pump (210)).Once the fluid flow from the PL cartridge has ceased, the fluid in thePL cartridge and the fluid in the transfer reservoir (408) may beentirely separate fluid entities. However, for some fluids, such asviscous fluids, there may be a fluid connection between the PL cartridge(200) and the transfer reservoir (408) even after the fluid flow fromthe PL cartridge has been stopped. In such a circumstance, if completefluid separation is desired, the control system (185) may advance thedisk assembly away from the dispense valve (206), as described below.The control system (185) may hold the sample in the transfer disk (302)as long as necessary, and may withhold the sample from testing if samplecontamination is suspected. When the control system (185) determinesthat the sensor disk (304) is ready to receive the fluid sample, thesample may be transferred from the transfer reservoir (408) to thesensor substrate (503). The fluid from the transfer reservoir (408) maybe transferred to the sensor substrate (503) through various methods,for example, gravity feed or pumping or otherwise actively moving asample, as described previously.

As previously mentioned, the timing of fluid transfer from the PLcartridge (200) to the transfer disk (302) to the sensor disk (304) maybe regulated by the control system (185). The control system (185) mayexecute different system functions between the stages of the fluid flow.For example, after the transfer of fluid from the PL cartridge (200) tothe transfer disk (302), the transfer disk may be advanced so that adifferent transfer reservoir (408) is positioned near the dispense valve(206). Before the fluid is moved from the transfer disk (302) to thesensor disk (304), the control system (185) may execute a calibrationprocedure to ready the sensor substrate (503) for sample testing. Anysystem configuration may be utilized to regulate the quantity,direction, and rate of fluid flow to optimally monitor analytes in thefluid sample. In some variations of a fluid monitoring device, themovement of fluid from a first location to a second location may beregulated so that the fluid connection between them is reduced oreliminated. For example, the fluid flow may be regulated to avoid acontinuous fluid column from the sensor substrate (503) to the PLcartridge (200). This type of fluid flow regulation may reduce oreliminate the back flow of any contaminants from the sensor substrate(503) to the patient line.

FIG. 9B illustrates an example of the path a fluid sample may take fromthe PL cartridge to the sensor substrate. Arrow (903) shows the path ofthe fluid sample from the PL cartridge, through the inlet (901) to thetransfer reservoir (408). The fluid is then transferred (by a variety ofmeans, such as gravity feed, by actively moving, displacing or bypumping) in the direction of arrow (906) to the outlet neck (417) to theoutlet (418). Cross-section T-T through the outlet (418) shows the pathof the fluid sample in the direction of arrow (907) down the outlet(418), towards the test sensor (502). The test sensor substrate (503)may be positioned to receive the fluid sample, for example, at alocation directly under or tangential to the outlet (418). Any excessfluid may be captured in a drain (522), and then channeled to anabsorbent material that prevents the fluid from contaminating unusedtest substrates. As previously described, various system functions maybe performed between the individual stages of this fluid flow (i.e. thestages indicated by arrows (903), (906), and (907)), such as advancingthe disk assembly, calibration procedures, and the like. The fluidsample may also be withheld indefinitely in the PL cartridge or thetransfer disk transfer reservoir as desired.

Separation of Sterile & Non-Sterile Components

In some variations of a fluid monitoring system, the fluid that ismonitored is patient blood. In such variations, the components thatcontact the patient's blood may be sterile to reduce the risk ofcontamination to the patient. A component may be manufactured using asterile process and facility, or may undergo a sterilization processpost-manufacture. In either case, the component may be packaged topreserve sterility. Some fluid monitoring systems may be manufacturedand assembled in a sterile environment, or may be assembled, thensterilized. In some variations, not all components of the fluidmonitoring system are sterilized. For example, the fluid lines in the PLand housing may be sterile, but the transfer disk and/or the sensor diskmay not be sterile. A barrier, such as a sterile membrane or a gap, maybe imposed between sterile and non-sterile components to reduce and/oreliminate contact between components. In some cases, the barrier may betemporary, such as packaging that is removed upon installation, orpermanent, such as air space between components. In other cases, thebarrier gap may be permanent, such as protrusions or spacers thatprovide permanent clearance between sterile and non sterile components.Additional steps may be taken during manufacture and installation toprotect sterilized components from contamination by non-sterilecomponents. For example, the packaging of a sterile PL and housing ordisk assembly may be sized and shaped so that the component can behandled and installed without contamination, as shown in FIGS. 10A and10B. Packaging (1000) may be used to protect the sterility of any systemcomponent, such as a PL cartridge or disk assembly. Packaging (1000) maycomprise a tray (1001) and lid (1003). The tray may be molded into ashape that fits the contours of the component it is intended to house,for example, the circular tray (1001) may be suitable for housing acomponent of the disk assembly, such as the transfer disk or sensordisk, and may be made of any material that provides sufficientstructural integrity to encase the enclosed component, such ashigh-density polyethylene (HDPE) or poly propylene. Some variations of atray may comprise latches or snap closures (1005) that retain thecomponent within the tray, as shown in FIG. 10C. Once the component isplaced inside tray (1001), the lid (1003) may be sealed over thecomponent. The lid (1003) may be made of any suitable material that canbe effectively sealed and bonded with the tray material, such as Tyvekfor a HDPE tray, or polycoated foil lid stock. The seal between lid(1003) and tray (1001) may be a heat seal, or an adhesive seal,according to the material composition of the lid and tray. Prior toinstallation, the lid (1003) may be removed, exposing the alignment andlocking features of the component, while the component remains seated(and engaged by latches (1005)) within the tray (1001). The latches(1005) or any alternate coupling mechanism is configured to engage thecomponent to the tray (1001) in a manner that prevents a user fromseparating the component from the tray, and thus preventing use of thecomponent in a manner that would compromise sterility. The tray (1001)may then be gripped to guide the component to the appropriateinstallation site, and manipulated so that the alignment and lockingfeatures of the component are fully engaged with the monitoring system.Full engagement and alignment with the fluid monitoring system may urgethe latches in the tray to disengage the component. The tray (1001) maythen be dissociated from the component and discarded. Other variationsof packaging (1000) and methods of installation may be used asappropriate for the component to be installed, where the packaging andmethod of handling reduces the contact of non-sterile items with thesterile component and may eliminate contamination by non-sterilecomponents along a sterile fluid pathway. During the manufacturingprocess, the different components may be treated and packagedseparately. For example, the transfer disk may be sterilized via gammairradiation, however, the sensor disk may not be sterilized. Directlyprior to use, the transfer disk and sensor disk may be assembled in thesame clean room, even those they are packaged separately.

The fluid monitoring system interface with the PL cartridge and diskassembly may have any suitable shape and size, with the appropriatelyaligned pins and recesses to accommodate the PL cartridge and diskassembly. One variation of an interface (1100) is shown in FIGS.11A-11B. The system interface (1100) has a recess (1101) for theinstallation of PL cartridge (200), and has a recess (1103) for theinstallation of disk assembly (300). There may also be additionalrecesses of varying shapes and sizes to accommodate additional systemcomponents, as well as apertures and snap closure to keep the PLcartridge and/or disk assembly components from disengaging from thesystem during use. The interface (1100) may also comprise sensor accessapertures (1105) for ready access to the disk assembly. Theblood-in-line, air-in-line, humidity and other sensor types may accessthe disk assembly through apertures such as (1109), (1111), and (1113)respectively.

FIG. 11B shows the housing provided by the fluid monitoring system,wherein the syringe may be installed prior to the PL cartridge (200).The recess (1103) may also comprise a protrusion that articulates withthe alignment features in the transfer disk (302). In this embodiment,the system interface (1100) is configured for the vertical installationof the disk assembly, but in other embodiments, the disk assembly may beoriented horizontally, or any position between the two. The intersectionbetween recess (1101) and recess (1103) may be configured so that thedisk assembly (300) and the PL cartridge (200) may not contact eachother when first installed, however a variety of actuators may be usedto adjust the distance between the disk assembly and PL cartridge.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A fluid monitoring system, comprising: apatient access interface configured to receive fluid from a patient; afluid pump configured to transfer fluid in the patient access interface;a valve coupled to the patient access interface and the fluid pump andcomprising a fluid dispensing opening, wherein the valve is configuredto dispense a fluid sample at the fluid dispensing opening; and a fluidinlet blocking structure adjacent to the fluid dispensing opening. 2.The fluid monitoring system of claim 1, wherein the patient accessinterface, fluid pump, valve and fluid inlet blocking structure arecoupled to a patient line housing.
 3. The fluid monitoring system ofclaim 1, further comprising an external fluid access interfaceconfigured to receive fluid from an external fluid source.
 4. A methodof performing fluid monitoring in a patient, comprising: withdrawingfluid from a patient into a first housing coupled to a fluid monitoringsystem; transferring a fluid sample from the withdrawn fluid in thefirst housing to a second housing; changing the orientation of thesecond housing relative to the first housing; pumping the fluid samplefrom the second housing to a test substrate.
 5. The method of claim 4,wherein pumping the fluid sample from the second housing to the testsubstrate comprises pumping the fluid sample across an air gap between afluid opening of the second housing and the test substrate.
 6. Themethod of claim 4, wherein pumping the fluid sample from the secondhousing to the test substrate comprises pumping the fluid sample fromthe second housing to a third housing, wherein the test substrate islocated in the third housing.
 7. The method of claim 4, furthercomprising wiping a dispensing region of the second housing.
 8. Themethod of claim 6, further comprising blocking an opening of the secondhousing the first housing.
 9. A method for performing fluid monitoringin a patient, comprising: transferring fluid along a first fluid pathwayfrom a patient to a fluid dispenser; transferring a fluid sample fromthe fluid dispenser to a transfer reservoir along a second fluidpathway; severing the second fluid pathway by displacing the transferreservoir; actively transferring at least a portion of the fluid samplefrom the transfer reservoir to a test substrate along a third fluidpathway.
 10. The method of claim 9, further comprising crossing an airgap between the transfer reservoir and the test substrate with the fluidsample.
 11. The method of claim 9, wherein at least portion of thecross-sectional shape of the fluid sample is unrestrained in atransverse plane along a movement axis of the third fluid pathway.
 12. Amethod for performing blood monitoring of a patient, comprising:withdrawing blood from a patient into a fluid control system; dispensinga blood sample from the sterile fluid control system to a steriletransfer reservoir; transferring the blood sample from the steriletransfer reservoir to an non-sterile test substrate.
 13. The method ofclaim 12, moving the sterile transfer reservoir with respect to thefluid control system after dispensing the blood sample.
 14. The methodof claim 13, wherein moving the sterile reservoir occurs beforetransferring the blood sample.
 15. The method of claim 12, whereintransferring the blood sample comprises pumping the blood sample fromthe sterile transfer reservoir to a non-sterile test substrate.